Note 8 - Common Stock and Common Stock Warrants - Reserved Shares of Common Stock for Future Issuances (Details) - shares	Dec. 31, 2022	Dec. 31, 2021
Reserved shares of common stock for future issuances (in shares)	26,291,959	4,570,924
Equity-based Awards [Member]
Reserved shares of common stock for future issuances (in shares)	1,001,087	2,131,671
Share-Based Payment Arrangement, Option [Member]
Reserved shares of common stock for future issuances (in shares)	4,570,432	2,439,253
Pre-funded and March 31, 2022 Warrants [Member]
Reserved shares of common stock for future issuances (in shares)	20,720,440	0