Auster

About the Raspberry Pi running 4K stuff, as it is still a computer, I’d imagine only through official streaming programs and not through browsers or unofficial players. Now, through Grayjay for Android I can play Crunchyroll videos (tested on a vanilla phone but Grayjay build is the same), and was able to run Amazon videos on vanilla Android on the Raspberry Pi 5, so I think it has potential as a streaming platform.

All ways give some form of data to Google, so I’d say the best ones are those that allow offline watch, like yt-dlp, Grayjay, etc., the ones with in-built DRM-free download options