There are export options for many music subscription services now, as well as apps like TuneMyMusic, Playlisty, etc. which can transfer your library and services between services.
I use Reduce Loud Sounds on the iPhone with my AirPods Pro to reduce the maximum volume to 80dB so that I don’t damage my hearing. That way, I can crank the volume buttons to maximum without having to think about it, knowing that it will be safe.
Hmm, I wasn’t able to output either just now after installing the Stremio flatpak on my SteamDeck. But I was able to get lossless 7.1 audio, which is nice. No Atmos, unfortunately.
Jellyfin still has a lot of catching up to do, unfortunately.