Lots of Jellyfin love in here, love too see it. The sever end of is great, the client end though... not so much. If you are just looking for a plug and go, plex has the maturity of their clients with a very workable backend. just about every device out there as an up to date official plex app, right down to a windows app if you really want it.
Again, no shit on Jellyfin here, Plex is a business after all.
It's getting better. On Android there's Findroid which does streaming really well, although it doesn't show most Jellyfin settings. Iirc there's also a native iOS app.