Hmmmm
Two nanos, a mini, a touch and a classic. Gonna plug them all in and see what still works, my guess is they all do. I know for sure the Nanos still work, plus the silver one, connected now, hand't been used in a year and the battery was still at 80%. The mini was a warranty replacement well after the factory warranty was depleted. I find that Apple generally does a better job with long term support than most others in the market.
[edit: yep, all still recognized by MacOS Big Sur]