Note 14 - Related-party Transactions (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended																12 Months Ended		72 Months Ended	96 Months Ended
	Jul. 20, 2023	Apr. 30, 2024		Jan. 31, 2024	[1]	Oct. 31, 2023	[1]	Jul. 31, 2023	[1]	Apr. 30, 2023		Jan. 31, 2023	[1]	Oct. 31, 2022	[1]	Jul. 31, 2022	[1]	Apr. 30, 2024	Apr. 30, 2023	Apr. 30, 2022	Apr. 30, 2024
Shares Acquired, Average Cost Per Share (in dollars per share)		$ 0.79	[1]	$ 0.73		$ 0.73		$ 0.73		$ 0.68	[1]	$ 0.68		$ 0.7		$ 0.84				$ 0.41	$ 0.63
Director David Hayden [Member] | Consulting Fees [Member]
Related Party Transaction, Amounts of Transaction																		$ 135	$ 135
Edgar Law Firm LLC [Member]
Related Party Transaction, Amounts of Transaction																		73	113
Chief Executive Officer [Member]
Accrued Liabilities, Current		$ 0								$ 244								$ 0	$ 244		$ 0
Shares Granted, Shares, Share-based Payment Arrangement, Forfeited (in shares)																		1,100,000
Severance Costs	$ 1,800
Stock Repurchased During Period, Shares (in shares)	1,933,402
Shares Acquired, Average Cost Per Share (in dollars per share)	$ 0.739
Vice President [Member]
Shares Granted, Shares, Share-based Payment Arrangement, Forfeited (in shares)																			800,000
Severance Costs	$ 2,700
Stock Repurchased During Period, Shares (in shares)	3,956,267
Shares Acquired, Average Cost Per Share (in dollars per share)	$ 0.739
Wayne Stewart [Member]
Compensation Expense, Excluding Cost of Good and Service Sold																		$ 315	$ 303
Craig Stewart [Member]
Compensation Expense, Excluding Cost of Good and Service Sold																		0	331
Jeff Shinkle [Member]
Compensation Expense, Excluding Cost of Good and Service Sold																		$ 162	$ 254

[1] These shares of common stock were purchased through a private transaction