Condensed Consolidated Statements of Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (unaudited) - USD ($) $ in Thousands	Total	Redeemable Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Balance at Dec. 31, 2019	$ (123,338)	$ 130,666		$ 4,419	$ (127,757)
Balance, Shares at Dec. 31, 2019		209,119,674	230,860
Issuance of Series C redeemable convertible preferred stock, net of issuance costs		$ 29,446
Issuance of Series C redeemable convertible preferred stock, net of issuance costs, Shares		78,306,611
Accretion of convertible preferred stock to redemption value	(115)			(115)
Temporary equity, Accretion of convertible preferred stock to redemption value		$ 115
Issuance of common stock warrants in conjunction with sale of Series C redeemable convertible preferred stock	740			740
Conversion of redeemable convertible preferred stock to common stock upon closing of initial public offering	160,227	$ (160,227)	$ 8	160,219
Conversion of redeemable convertible preferred stock to common stock upon closing of initial public offering, Shares		(287,426,285)	8,335,248
Issuance of common stock from initial public offering, net of issuance costs	57,284		$ 4	57,280
Issuance of common stock from initial public offering, net of issuance costs, Shares			4,025,000
Vesting of restricted common stock			19,661
Issuance of common stock upon exercise of warrants			$ 1	(1)
Issuance of common stock upon exercise of warrants, Shares			313,794
Exercise of common stock options	1			1
Exercise of common stock options, Shares			254
Stock-based compensation	1,221			1,221
Net loss	(15,106)				(15,106)
Balance at Sep. 30, 2020	80,914		$ 13	223,764	(142,863)
Balance, Shares at Sep. 30, 2020			12,924,817
Balance at Jun. 30, 2020	86,823		$ 13	223,339	(136,529)
Balance, Shares at Jun. 30, 2020			12,924,563
Issuance of common stock from initial public offering, net of issuance costs	(44)			(44)
Exercise of common stock options	1			1
Exercise of common stock options, Shares			254
Stock-based compensation	468			468
Net loss	(6,334)				(6,334)
Balance at Sep. 30, 2020	80,914		$ 13	223,764	(142,863)
Balance, Shares at Sep. 30, 2020			12,924,817
Balance at Dec. 31, 2020	74,492		$ 13	224,363	(149,884)
Balance, Shares at Dec. 31, 2020			12,932,377
Exercise of common stock options	$ 604			604
Exercise of common stock options, Shares	72,201		72,201
Stock-based compensation	$ 1,988			1,988
Net loss	(29,896)				(29,896)
Balance at Sep. 30, 2021	47,188		$ 13	226,955	(179,780)
Balance, Shares at Sep. 30, 2021			13,004,578
Balance at Jun. 30, 2021	57,499		$ 13	226,211	(168,725)
Balance, Shares at Jun. 30, 2021			13,001,105
Exercise of common stock options	11			11
Exercise of common stock options, Shares			3,473
Stock-based compensation	733			733
Net loss	(11,055)				(11,055)
Balance at Sep. 30, 2021	$ 47,188		$ 13	$ 226,955	$ (179,780)
Balance, Shares at Sep. 30, 2021			13,004,578