Piggyback to share what I’ve tried:

YouTube plugin for Kodi on rpi 4B - great when it worked, often had breaking bugs for a long time (cat and mouse development), somewhat difficult to keep up to date. Had to manually install releases from github.

“Play on Kodi” add on, which uses ytdlp to download and send the video. Fiddly, could never get it to work seamlessly or smoothly.

YouTube in firefox on RaspberryOS, with keyboard and mouse: firefox was too heavy for the rpi to work consistently.

I eventually bought one of those beelink mini pcs, which has enough power to run Firefox, to watch YouTube. It doesn’t have CEC built in, which is a huge downgrade, but the YouTube experience is great, and it can easily watch videos on other Web sites too.