Rockbox runs on apple ipods. Best thing to do is always buying a device compatible with open source software if you plan to use it fir years on end.

I bought one of those used for my daughter a couple of years ago. It was quite the hassle to replace the apple firmware win with rockbox, but it’s been working well since then. It’s copy and paste mp3s now instead of using apples spying bloatware just to get a few files onto the device. The battery is not great but still lasts a couple of hours after 15(?) years.