At first I thought about something like https://libreelec.tv/ but Kodi instead of the much more powerful mpv is not an option.

So probably a custom lightweight distro with mpv outputting to DRM directly and a game controller to navigate some file explorer ? Maybe try to script around some speech-to-text LLM to be able to say "Play me X", heh.

Or just control it via ssh because that's actually simpler for me.