install something debian-like and then try jellyfin-mpv-shim and then add macast. you’re creating a sink that plays whatever you send it via your mobile device. so, no interface on the tv to navigate, you browse your jellyfin library from your phone and just send it to the player. you control the playback from the mobile app (play, stop, volume, change subs, etc). behind the scene it uses mpv to play the video.
macast does the same for online videos e.g youtube, vimeo, etc. you send it a youtube video and it plays it in fullscreen. behind the scenes it uses yt-dl with mpv.