Yup! I use Mobius on iOS to sync everything I want, including random one off file transfers, but mostly to keep my Keepass database and Obsidian vault in sync across devices. It works really well, despite apple making it super difficult to run consistently in the background. As long as you open the app every so often, it’s seamless and reliable.

Syncthing.

Totally understandable. I was hesitant about it too, but to me it’s sometimes worth a premium to get something that just works, and Infuse works better than any player I’ve used in the past. To each their own, good luck!

As suggested above, I would try Infuse player. I recently switched from a Kodi/Jellyfin setup to an Apple TV/Jellyfin setup and I’m extremely happy with it. Infuse has a free trial, and then you can choose to pay a few different ways (they do have a rather expensive lifetime option, but it might be worth it). The Infuse app has no trouble playing directly from my Jellyfin server, no transcoding, even for full 4K Bluray rips, and yes it even supports Dolby Vision (which the native Jellyfin app struggles with). No hiccups, no issues with multiple audio tracks or subtitles, it’s just buttery smooth direct playback.

It also has a couple different ways of interacting with your Jellyfin library, so it feels completely seamless to me.

Same, Syncthing is amazing. I use it with Mobius Sync on iOS and have it synching my keepass, Obsidian vault, photos, and a folder for random file transfers between devices. It’s so much better, faster, and more stable than all the most popular corporate cloud providers.