I’m using Jellyfin with 2 Apple TV 4Ks, one newer and one older. As other commenters have said there is no complete official Jellyfin app for Apple TV.

Swiftfin is the in development new app for Apple platforms, but it still very incomplete. Basic video playback works, but there are a lot of missing features like music and live tv support. The interface is functional but still fairly crude, and in the current version there’s a lot of ugly overflow issues in the UI. Video playback has always been reliable for me though. It will improve as development progresses but for now it’s very much a work in progress.

The other option is Infuse, which has a much nicer and mature UI, but also isn’t fully feature complete for Jellyfin. It also a proprietary app with a subscription to unlock all features. I’ve tried the free version and it seems to work well enough, video playback was smooth.

I think there are few other small apps but I haven’t tried them.

I wish there were better options for clients as the Apple TV is the best streaming box I’ve found but the Jellyfin support could be better.

I just hope the shockwave doesn’t knock down the rest of the economy with it.