I've been running Plex on my AppleTV 4k for years with few issues.

It gets a lot of use in my household. I have my server (a headless Intel iGPU box) running it in docker with the Intel iGPU encoder passed through.

I let the iGPU default encode everything realtime, and now that plex has automatic subtitle sync, my main source of complaints is gone. I end up with a wide variety of formats as my wife enjoys obscure media.

One of the key things that helped a lot was segregating Anime to it own TV collection so that anime specific defaults can be applied there.

You can also run a client on one of these machines directly, but then you are dealing with desktop Linux.