Interesting topic!
Previously I had a highend Linux HTPC, with Ryzen 7 3700x and RTX3060ti graphics etc.
A month ago I bought a Sony Bravia Android TV. I was very impressed that I could just load Kodi from Play store and it would work right out of the box. Kodi feels the same as on the HTPC, it's not noticeably slower. 4K HDR is working nicely, etc.
I used my HTPC for Steam games as well. Turns out I can run most of my games with Geforce Now, directly on the TV with no external hardware! That was the last nail in the coffin. HTPC no more, just TV.
However, now that I have used the TV for a month, there are some issues which are starting to grow on me, to such point that I'm considering buying a Nvidia Shield.. But maybe not yet.
1)
TV only has 100Mb ethernet. Can't understand the reasoning for this. I have 4K videos on a network share, they are struggling. And I'm not talking about pirated movies, these are output from my 4K BlackVue car camera which automatically backups to the network drive.. What's more, it's not just Kodi saying "source too slow", sometimes it manages to flood the ethernet so that all connections drop and then it takes like 30seconds to return to normal.
However, TV does have very fast Wifi. Everything works much better if I simply unplug the ethernet. So this problem is perhaps "solved".
I bought a few more wifi routers so I could place one right next to the TV. It connects at 866MBps, and even iperf3 speedtest confirms >500M speeds in my LAN.
2)
Sony runs Android TV in 60fps fixed mode... The framerate API is not supported so Kodi can't change it. Kodi plays everything in 60fps. However this is not as bad as it sounds. 30fps and 60fps play fine, of course. Most movies are 24fps, Kodi plays them with 3:2 conversion to get 60fps. Sony's "cinema mode" logic detects this and actually converts it to 120fps 5:5, which looks good. If you don't enable Motion Flow it looks exactly the same as real 24fps.
25fps is common in PAL TV (Europe). That's tricky. Kodi has to play that in 60fps too, which results in jumping and skipping because 60fps is not exact multiple of 25fps. Sony doesn't seem to be able to revert that, especially when the target 120fps is not a multiple of 25fps either. But luckily if you enable Motion Flow it looks reasonably good for regular TV viewing. Movies and other "important sources" are 24fps anyway.
3)
Sound. Sony allows only Stereo, Dolby Digital, DTS, or Dolby Digital+ for android apps like Kodi. No multichannel PCM!
However Dolby Digital+ has very high bitrate and allows multichannel (even Dolby Atmos!). For me that is good enough. Kodi plays files with DD+ audio just fine, with 7.1 audio. But if you have movie with AAC or PCM audio, Kodi will have to transcode that to Dolby Digital 5.1... It would be great if Kodi could transcode into DD+, but that's perhaps not happening.