Note 1 - Basis of Presentation and Significant Accounting Policies - Option Activity (Details) - $ / shares	6 Months Ended	12 Months Ended
	Mar. 31, 2022	Sep. 30, 2021
Options, Outstanding Balance (in shares)	1,853,479
Weighted Average Exercise Price, Outstanding Balance (in dollars per share)	$ 4.44
Weighted Average Remaining Contractual Period in Years, Outstanding Ending Balance (Year)	7 years 1 month 28 days	4 years 7 months 6 days
Options, Granted (in shares)	851,250
Weighted Average Exercise Price, Granted (in dollars per share)	$ 3.23
Weighted Average Remaining Contractual Period in Years, Granted (Year)	9 years 10 months 13 days
Options, Exercised (in shares)	(66,851)
Weighted Average Exercise Price, Exercised (in dollars per share)	$ 1.59
Weighted Average Remaining Contractual Period in Years, Exercised (Year)	6 years 10 months 24 days
Options, Forfeited and cancelled (in shares)	(158,519)
Weighted Average Exercise Price,Forfeited and cancelled (in dollars per share)	$ 5.92
Options, Outstanding at end of year (in shares)	2,479,359	1,853,479
Weighted Average Exercise Price, Outstanding Balance (in dollars per share)	$ 4.00	$ 4.44
Options, Exercisable at end of year (in shares)	1,348,377
Weighted Average Exercise Price, Exercisable (in dollars per share)	$ 4.63
Weighted Average Remaining Contractual Period in Years, Exercisable Ending Balance (Year)	5 years 4 months 2 days