Note 6 - Equity and Stock-based Compensation - Stock Option Activity (Details) - The 2016 Omnibus Plan [Member] - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Shares outstanding (in shares)	1,355,001
Shares outstanding, weighted-average exercise price (in dollars per share)	$ 0.52
Shares outstanding, weighted-average remaining contractual term (Year)	6 years 6 months 29 days	3 years 10 months 24 days
Shares granted (in shares)	1,181,666
Shares granted, weighted-average exercise price (in dollars per share)	$ 0.69
Shares granted, weighted-average remaining contractual term (Year)	10 years
Shares exercised (in shares)	0
Shares exercised, weighted-average exercise price (in dollars per share)	$ 0
Shares forfeited or expired (in shares)	0
Shares forfeited or expired, weighted-average exercise price (in dollars per share)	$ 0
Shares outstanding (in shares)	2,536,667	1,355,001
Shares outstanding, weighted-average exercise price (in dollars per share)	$ 0.60	$ 0.52
Shares exercisable (in shares)	2,103,334
Shares exercisable, weighted-average exercise price (in dollars per share)	$ 0.57
Shares exercisable, weighted-average remaining contractual term (Year)	5 years 10 months 20 days