I think older versions of the kernel (that support 486 hw) would still be available to download so someone could use them if they wanted. Not sure what other extre work would be involved though.

I’ve only ever used jellyfin and have no complaints.

I avoided plex and went with jellyfill because it’s free/libre software.

If you’re OK with using non-free/libre software I reccomend the systemcrafters install guide

https://systemcrafters.net/craft-your-system-with-guix/full-system-install/