Note 8 - Stockholders' Equity - Shares of Common Stock Reserved for Issuance (Details) - shares	Sep. 30, 2025	Dec. 31, 2024
Common stock reserved for issuance (in shares)	44,333,608	45,575,342
Common Warrants [Member]
Common stock reserved for issuance (in shares)	10,914	140,596
The 2019 Plan [Member]
Common stock reserved for issuance (in shares)	10,684,202	18,046,374
The 2024 Inducement Award Plan [Member]
Common stock reserved for issuance (in shares)	43,250	1,603,750
Share-Based Payment Arrangement, Option [Member]
Common stock reserved for issuance (in shares)	25,668,404	20,405,239
Restricted Stock Units (RSUs) [Member]
Common stock reserved for issuance (in shares)	5,779,522	3,016,481
ESPP [Member]
Common stock reserved for issuance (in shares)	2,147,316	2,362,902