I honestly don’t know if \e\ is interested to support “non libre” services as Youtube (as author I certainly prefer Vimeo wich supports ALL Creative Commons licenses), anyway many “common users” needs it.
So here’s Smart YouTube TV an open source Youtube client for Android TVs (but easily portable on standard devices quite easily I believe):
Features
4K support
**runs without Google Services**
designed for TV screens
stock controller support
multilingual search keyboard
fully localized
https://smartyoutubetv.github.io
Hope that inspires.