Stock-based compensation - Option details (Details) - $ / shares	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 0.3082
Number of options issued and outstanding (in shares)	66,995,224	50,717,724
Number of vested options outstanding (in shares)	15,875,099
Number of unvested options outstanding (in shares)	51,120,125
July 9, 2020
Share-based compensation
Exercise Price (in dollars per share)	$ 0.18
Number of options issued and outstanding (in shares)	175,000
Number of vested options outstanding (in shares)	131,250
Number of unvested options outstanding (in shares)	43,750
Weighted avg remaining life outstanding	2 years 9 months 10 days
August 25, 2020
Share-based compensation
Exercise Price (in dollars per share)	$ 0.13
Number of options issued and outstanding (in shares)	20,000
Number of vested options outstanding (in shares)	10,000
Number of unvested options outstanding (in shares)	10,000
Weighted avg remaining life outstanding	2 years 10 months 24 days
October 1, 2020
Share-based compensation
Exercise Price (in dollars per share)	$ 0.11
Number of options issued and outstanding (in shares)	266,667
Number of vested options outstanding (in shares)	116,667
Number of unvested options outstanding (in shares)	150,000
Weighted avg remaining life outstanding	3 years 3 days
October 20, 2020
Share-based compensation
Exercise Price (in dollars per share)	$ 0.09
Number of options issued and outstanding (in shares)	20,000
Number of vested options outstanding (in shares)	10,000
Number of unvested options outstanding (in shares)	10,000
Weighted avg remaining life outstanding	3 years 21 days
March 1, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 2.06
Number of options issued and outstanding (in shares)	200,000
Number of vested options outstanding (in shares)	100,000
Number of unvested options outstanding (in shares)	100,000
Weighted avg remaining life outstanding	8 years 5 months 1 day
March 8, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 1.88
Number of options issued and outstanding (in shares)	200,000
Number of vested options outstanding (in shares)	100,000
Number of unvested options outstanding (in shares)	100,000
Weighted avg remaining life outstanding	8 years 5 months 8 days
March 15, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 2.49
Number of options issued and outstanding (in shares)	200,000
Number of vested options outstanding (in shares)	100,000
Number of unvested options outstanding (in shares)	100,000
Weighted avg remaining life outstanding	8 years 5 months 15 days
May 12, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 0.78
Number of options issued and outstanding (in shares)	3,400,000
Number of vested options outstanding (in shares)	850,000
Number of unvested options outstanding (in shares)	2,550,000
Weighted avg remaining life outstanding	8 years 7 months 13 days
May 14, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 0.75
Number of options issued and outstanding (in shares)	3,200,000
Number of vested options outstanding (in shares)	850,000
Number of unvested options outstanding (in shares)	2,350,000
Weighted avg remaining life outstanding	8 years 7 months 13 days
August 18, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 0.50
Number of options issued and outstanding (in shares)	200,000
Number of vested options outstanding (in shares)	50,000
Number of unvested options outstanding (in shares)	150,000
Weighted avg remaining life outstanding	8 years 10 months 20 days
August 23, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 0.50
Number of options issued and outstanding (in shares)	100,000
Number of vested options outstanding (in shares)	25,000
Number of unvested options outstanding (in shares)	75,000
Weighted avg remaining life outstanding	8 years 10 months 24 days
September 13, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 0.57
Number of options issued and outstanding (in shares)	800,000
Number of vested options outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	600,000
Weighted avg remaining life outstanding	8 years 11 months 15 days
October 01, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 0.58
Number of options issued and outstanding (in shares)	12,650,000
Number of unvested options outstanding (in shares)	12,650,000
Weighted avg remaining life outstanding	9 years 3 days
January 3, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.36
Number of options issued and outstanding (in shares)	100,000
Number of unvested options outstanding (in shares)	100,000
Weighted avg remaining life outstanding	9 years 3 months 7 days
January 4, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.35
Number of options issued and outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	200,000
Weighted avg remaining life outstanding	9 years 3 months 7 days
January 14, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.35
Number of options issued and outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	200,000
Weighted avg remaining life outstanding	9 years 3 months 18 days
January 16, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.35
Number of options issued and outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	200,000
Weighted avg remaining life outstanding	9 years 3 months 18 days
January 18, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.35
Number of options issued and outstanding (in shares)	100,000
Number of unvested options outstanding (in shares)	100,000
Weighted avg remaining life outstanding	9 years 3 months 21 days
February 14, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.30
Number of options issued and outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	200,000
Weighted avg remaining life outstanding	9 years 4 months 17 days
February 21, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.37
Number of options issued and outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	200,000
Weighted avg remaining life outstanding	9 years 4 months 24 days
February 25, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.35
Number of options issued and outstanding (in shares)	12,300,000
Number of unvested options outstanding (in shares)	12,300,000
Weighted avg remaining life outstanding	9 years 4 months 28 days
March 30, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.35
Number of options issued and outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	200,000
Weighted avg remaining life outstanding	9 years 6 months
April 1, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.34
Number of options issued and outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	200,000
Weighted avg remaining life outstanding	9 years 6 months 3 days
April 6, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.32
Number of options issued and outstanding (in shares)	100,000
Number of unvested options outstanding (in shares)	100,000
Weighted avg remaining life outstanding	9 years 6 months 7 days
April 11, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.31
Number of options issued and outstanding (in shares)	75,000
Number of unvested options outstanding (in shares)	75,000
Weighted avg remaining life outstanding	9 years 6 months 14 days
May 2, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.25
Number of options issued and outstanding (in shares)	300,000
Number of unvested options outstanding (in shares)	300,000
Weighted avg remaining life outstanding	9 years 7 months 2 days
May 9, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.21
Number of options issued and outstanding (in shares)	700,000
Number of unvested options outstanding (in shares)	700,000
Weighted avg remaining life outstanding	9 years 7 months 9 days
May 11, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.20
Number of options issued and outstanding (in shares)	400,000
Number of unvested options outstanding (in shares)	400,000
Weighted avg remaining life outstanding	9 years 7 months 13 days
May 16, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.23
Number of options issued and outstanding (in shares)	100,000
Number of unvested options outstanding (in shares)	100,000
Weighted avg remaining life outstanding	9 years 7 months 17 days
May 31, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.24
Number of options issued and outstanding (in shares)	500,000
Number of unvested options outstanding (in shares)	500,000
Weighted avg remaining life outstanding	9 years 8 months 1 day
June 1, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.25
Number of options issued and outstanding (in shares)	500,000
Number of unvested options outstanding (in shares)	500,000
Weighted avg remaining life outstanding	9 years 8 months 4 days
June 6, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.26
Number of options issued and outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	200,000
Weighted avg remaining life outstanding	9 years 8 months 8 days
June 13, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.24
Number of options issued and outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	200,000
Weighted avg remaining life outstanding	9 years 8 months 15 days
July 1 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.21
Number of options issued and outstanding (in shares)	350,000
Number of unvested options outstanding (in shares)	350,000
Weighted avg remaining life outstanding	9 years 9 months 3 days
July 5 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.22
Number of options issued and outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	200,000
Weighted avg remaining life outstanding	9 years 9 months 7 days
July 6 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.26
Number of options issued and outstanding (in shares)	100,000
Number of unvested options outstanding (in shares)	100,000
Weighted avg remaining life outstanding	9 years 9 months 7 days
July 25 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.25
Number of options issued and outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	200,000
Weighted avg remaining life outstanding	9 years 9 months 25 days
August 1 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.28
Number of options issued and outstanding (in shares)	100,000
Number of unvested options outstanding (in shares)	100,000
Weighted avg remaining life outstanding	9 years 10 months 2 days
August 5 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.34
Number of options issued and outstanding (in shares)	2,850,000
Number of unvested options outstanding (in shares)	2,850,000
Weighted avg remaining life outstanding	9 years 10 months 6 days
August 8 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.39
Number of options issued and outstanding (in shares)	100,000
Number of unvested options outstanding (in shares)	100,000
Weighted avg remaining life outstanding	9 years 10 months 9 days
August 17 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.31
Number of options issued and outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	200,000
Weighted avg remaining life outstanding	9 years 10 months 20 days
August 19 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.27
Number of options issued and outstanding (in shares)	400,000
Number of unvested options outstanding (in shares)	400,000
Weighted avg remaining life outstanding	9 years 10 months 20 days
August 22 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.27
Number of options issued and outstanding (in shares)	400,000
Number of unvested options outstanding (in shares)	400,000
Weighted avg remaining life outstanding	9 years 10 months 24 days
August 29 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.27
Number of options issued and outstanding (in shares)	400,000
Number of unvested options outstanding (in shares)	400,000
Weighted avg remaining life outstanding	9 years 11 months 1 day
August 31 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.25
Number of options issued and outstanding (in shares)	800,000
Number of unvested options outstanding (in shares)	800,000
Weighted avg remaining life outstanding	9 years 11 months 4 days
September 6 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.21
Number of options issued and outstanding (in shares)	75,000
Number of unvested options outstanding (in shares)	75,000
Weighted avg remaining life outstanding	9 years 11 months 8 days
September 21 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.23
Number of options issued and outstanding (in shares)	200,000
Number of unvested options outstanding (in shares)	200,000
Weighted avg remaining life outstanding	9 years 11 months 23 days
September 23 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.21
Number of options issued and outstanding (in shares)	400,000
Number of unvested options outstanding (in shares)	400,000
Weighted avg remaining life outstanding	9 years 11 months 26 days
September 26 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.22
Number of options issued and outstanding (in shares)	300,000
Number of unvested options outstanding (in shares)	300,000
Weighted avg remaining life outstanding	10 years
Grantee One | March 14, 2020
Share-based compensation
Exercise Price (in dollars per share)	$ 0.19
Number of options issued and outstanding (in shares)	75,000
Number of vested options outstanding (in shares)	75,000
Weighted avg remaining life outstanding	3 days
Grantee One | December 31, 2020
Share-based compensation
Exercise Price (in dollars per share)	$ 0.23
Number of options issued and outstanding (in shares)	125,000
Number of vested options outstanding (in shares)	125,000
Weighted avg remaining life outstanding	3 days
Grantee One | February 26, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 1.87
Number of options issued and outstanding (in shares)	100,000
Number of vested options outstanding (in shares)	100,000
Weighted avg remaining life outstanding	2 months 19 days
Grantee One | August 11, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 0.57
Number of options issued and outstanding (in shares)	50,000
Number of vested options outstanding (in shares)	50,000
Weighted avg remaining life outstanding	1 month 24 days
Grantee One | June 17, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.24
Number of options issued and outstanding (in shares)	375,000
Number of vested options outstanding (in shares)	375,000
Weighted avg remaining life outstanding	2 years 5 months 12 days
Grantee Two | March 14, 2020
Share-based compensation
Exercise Price (in dollars per share)	$ 0.19
Number of options issued and outstanding (in shares)	37,500
Number of vested options outstanding (in shares)	37,500
Weighted avg remaining life outstanding	2 months 15 days
Grantee Two | December 31, 2020
Share-based compensation
Exercise Price (in dollars per share)	$ 0.23
Number of options issued and outstanding (in shares)	50,000
Number of vested options outstanding (in shares)	50,000
Weighted avg remaining life outstanding	2 months 15 days
Grantee Two | February 26, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 1.87
Number of options issued and outstanding (in shares)	200,000
Number of vested options outstanding (in shares)	100,000
Number of unvested options outstanding (in shares)	100,000
Weighted avg remaining life outstanding	8 years 4 months 28 days
Grantee Two | August 11, 2021
Share-based compensation
Exercise Price (in dollars per share)	$ 0.57
Number of options issued and outstanding (in shares)	900,000
Number of vested options outstanding (in shares)	225,000
Number of unvested options outstanding (in shares)	675,000
Weighted avg remaining life outstanding	8 years 10 months 13 days
Grantee Two | June 17, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.24
Number of options issued and outstanding (in shares)	225,000
Number of vested options outstanding (in shares)	225,000
Weighted avg remaining life outstanding	3 years
Grantee Three | March 14, 2020
Share-based compensation
Exercise Price (in dollars per share)	$ 0.19
Number of options issued and outstanding (in shares)	1,133,557
Number of vested options outstanding (in shares)	837,182
Number of unvested options outstanding (in shares)	296,375
Weighted avg remaining life outstanding	2 years 5 months 12 days
Grantee Three | December 31, 2020
Share-based compensation
Exercise Price (in dollars per share)	$ 0.23
Number of options issued and outstanding (in shares)	15,742,500
Number of vested options outstanding (in shares)	8,632,500
Number of unvested options outstanding (in shares)	7,110,000
Weighted avg remaining life outstanding	8 years 3 months
Grantee Three | June 17, 2022
Share-based compensation
Exercise Price (in dollars per share)	$ 0.24
Number of options issued and outstanding (in shares)	2,500,000
Number of vested options outstanding (in shares)	2,500,000
Weighted avg remaining life outstanding	8 years 3 months 3 days