Note 2 - Summary of Significant Accounting Policies - Revision of Prior Period (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Product revenue, net	$ 3,826			$ 2,265			$ 10,761	$ 7,031
Product cost of goods sold	1,451			712			4,735	2,194
Sales and marketing	1,835			2,061			5,860	5,942
Net loss	$ (136)	$ (2,155)	$ (111)	$ (2,289)	$ (1,859)	$ (1,518)	$ (2,402)	$ (5,666)
Net loss per share (basic and diluted) (in dollars per share)	$ (0.10)			$ (0.05)			$ (0.15)	$ (0.13)
Previously Reported [Member]
Sales and marketing	$ 1,570			$ 1,855			$ 5,009	$ 5,323
Net loss	$ (136)			$ (2,289)			$ (2,402)	$ (5,666)
Net loss per share (basic and diluted) (in dollars per share)	$ (0.10)			$ (0.05)			$ (0.15)	$ (0.13)
Revision of Prior Period, Change in Accounting Principle, Adjustment [Member] | Change in Accounting for Selling Commissions [Member]
Sales and marketing	$ 265			$ 206			$ 851	$ 619
Net loss	$ 0			$ 0			$ 0	$ 0
Net loss per share (basic and diluted) (in dollars per share)	$ 0			$ 0			$ 0	$ 0
Revision of Prior Period, Change in Accounting Principle, Adjustment [Member] | Change in Accounting for Fulfillment Fees [Member]
Sales and marketing	$ 0						$ 0
Net loss	$ 0			$ 0			$ 0	$ 0
Net loss per share (basic and diluted) (in dollars per share)	$ 0			$ 0			$ 0	$ 0
Product [Member]
Product revenue, net	$ 3,816			$ 2,259			$ 10,743	$ 7,012
Product cost of goods sold	1,451			712			4,735	2,194
Product [Member] | Previously Reported [Member]
Product revenue, net	3,268			1,834			8,934	5,761
Product cost of goods sold	1,168			493			3,776	1,562
Product [Member] | Revision of Prior Period, Change in Accounting Principle, Adjustment [Member] | Change in Accounting for Selling Commissions [Member]
Product revenue, net	265			206			851	619
Product cost of goods sold	0						0
Product [Member] | Revision of Prior Period, Change in Accounting Principle, Adjustment [Member] | Change in Accounting for Fulfillment Fees [Member]
Product revenue, net	283			219			959	632
Product cost of goods sold	$ 283			$ 219			$ 959	$ 632