Note 12 - Stock Options and Incentive Plans - Restricted Stock Options Activity (Details) - $ / shares	3 Months Ended	12 Months Ended	37 Months Ended
	Jul. 31, 2023	Apr. 30, 2023	Apr. 30, 2022
Outstanding, shares (in shares)			7,900,000
Outstanding, weighted average fair value (in dollars per share)			$ 0.42
Forfeited, shares (in shares)	(1,300,000)	(875,000)	(100,000)
Forfeited, weighted average fair value (in dollars per share)	$ 0.40	$ 0.40	$ 0.40
Outstanding, shares (in shares)	5,625,000
Outstanding, weighted average fair value (in dollars per share)	$ 0.43