I don't understand why anyone continues to give Plex the time of day. Jellyfin has far and away eclipsed them.
Plex client is available almost everywhere and overall, Plex mostly "just works". The latest Apple TV client changes have me hot and there are things I don't love but that's what's kept me in the Plex ecosystem. I am looking around now though since I'm so disappointed with the new clients/UI.
As far as I understand it Jellyfin has been improving client availability and to me seems to work well for friends.
* a native Xbox app (I believe Jellyfin may now have one)
* non-techie acceptance (Plex seemed more polished at the time, will need to reassess now)
Either way, I'll be warning my spouse that things may be changing soon.