Moonlight works really well on the ATV4K too. I stream 4K@60FPS with HDR and surround sound from my PC using the Apollo fork of Sunshine (creates a virtual display since I normally game at 1440p on my attached monitor).
*I do have a once-per-run Moonlight glitch that may even be because I'm on an older version. The first connection just doesn't pick up on the HDR immediately. I just have to reconnect once and it's good after that.
[1]: https://github.com/ClassicOldSong/Apollo ("Built-in Virtual Display with HDR support that matches the resolution/framerate config of your client automatically")