I’d think most people woud go for a cheap used ultra Small Form Factor pc or raspberry pi set up as an htpc. Plug in to either tv screen (via hdmi ) or monitor / projector directly. Never connect the tv to the internet - or even to your LAN if you’re really paranoid. You can arse around with a remote control a bit bodgy, or just use wireless Keyboard/mouse.

I cant imagine spending the time to jailbreak a tv to get less functionality for more hassle - but i’m sure some crazy will have done it - good luck finding them though.