Some Xiaomi TVs have root exploits, so you can manually disinfect the OS, but it's cumbersome to get done since you need to enter adb commands over the remote control to get there in the first place.

Easier to just use an external device and the TV as a screen only. Personally I'm using the Nvidia Shield for 5+ years now and regret nothing.

Not ideal, but you can air gap the TV from the network, and use some small sbc, or even a firestick or android box. That's what I do. Stremio?