you can still sync music to iPods using the music app/the finder on mac [0]. there’s a similar thing for windows as well [1]. on linux, i know the clementine music player supports iPod sync [2]. all these options let you use the original firmware!

0: https://support.apple.com/en-gb/guide/mac-help/mchlde9a31f1/...

1: https://support.apple.com/en-ca/guide/devices-windows/mchlbf...

2: https://github.com/clementine-player/Clementine/wiki/Portabl...

It is actually still supported directly Finder on macOS. Or, even better, just putting Rockbox on them and copying files over directly, and that’s well supported in Linux.

Pricing on the used market is maybe a bit high compared to some of the other options out there but the hardware still feels great and there’s massive aftermarket support so there are still benefits to an iPod.