When I had an android TV I used Proton VPN frequently. Since I have switched to Titan OS this is one of the things I miss.
OS Website: titanos.tv
Runs on my latest Philps TV. It is a European operating system.

There is currently no VPN app available as far as I know on Titan OS. I don't know if it is possible to build within their SDK; but if it is it could be a good opportunity for Proton to get in there first.