Note 13 - Fair Value of Financial Instruments - Estimate Fair Value of Financial Instruments (Details)	Sep. 27, 2020 $ / shares yr	Sep. 29, 2019 $ / shares yr	Sep. 30, 2018 $ / shares yr
Measurement Input, Price Volatility [Member]
Warrant and rights, measurement input	0.84	0.48	0.31
Measurement Input, Risk Free Interest Rate [Member]
Warrant and rights, measurement input	0.0012	0.0158	0.0291
Measurement Input, Expected Term [Member]
Warrant and rights, measurement input | yr	1.5	2.5	3.5
Measurement Input, Share Price [Member]
Warrant and rights, measurement input | $ / shares	0.06	0.20	0.3