It'll be difficult. It's webos of which there's very little custom development.
You'd be better off with an android tv which you can poke at using adb and disable services. Maybe even root it. And install alternative software like smarttubenext.
Unfortunately there very few Android based TVs left. Phillips recently switched to Titanos, Samsung has tizen, Amazon has a new OS. I think it's just Sony that's left on android now.
Surely the Astras and Fables of this world would make light work of setting up a WebOS build environment and be able to create practically any changes you can think of, especially if there is a way for them to iterate the development.