Rusty CorgiOh my gosh yessss there's finally a LibAdwaita music player that supports Jellyfin. 
Nocturne just added Jellyfin support and, based on playing around with it for a bit, it works shockingly well despite being labelled experimental.
It's so nice I am SO EXCITED 
It was initially released as a local music/Subsonic/Navidrome player, so if those are more your speed, it also supports them. 
Sominemo