jellysub VS gelli

For the Jellyfin API it might be worth adding https://github.com/nvllsvm/jellysub, it's an API compatibility layer to let Subsonic-compatible apps query Jellyfin.

Subsonic

You can just use the music player app from your android phone to connect your jellyfin. Such as gelli or finamp

You could try Jellyfin as a media server, it has various Android apps that can stream from it that work quite well. I haven't made up my mind yet which one I prefer, so I use both interchangeably: Gelli and Finamp.

That's true, Plex has been around a long time and it's on a lot of devices. I've been using Gelli (https://github.com/dkanada/gelli) as a music player for JellyFin on my phone for a while now and it's great.

I use both. In the web browser, I prefer Navidrome because it's more lightweight. For native mobile client, I use Gelli with Jellyfin and Subtracks with Navidrome. However, I prefer Gelli to Subtracks for its UI and features.

Highly recommend one of the dedicated music apps for music playback on mobile, I use Finamp and have used Gelli in the past.

If your brother isn't fan of the interface, and is willing to sideload, Gelli has some customization and is generally more polished in terms of animations and interations. It's also on F-Droid, an alternative to the play store, here. It does not have offline mode which can be a dealbreaker.

I also use Finamp for audio streaming (or local, downloaded playback). It's a good app, but still lacking a lot of features other audio players have, like rearranging the play queue. I'd suggest also trying [Gelli](https://github.com/dkanada/gelli), which seems to be a more mature app for music playback.

There are a few for jellyfin, Gelli being the one I use

And Gelli