The app NewPipe and its web version https://invidio.us/ were recommended in the comments here. They allow you to use YouTube quite well without an account and without the official website/app. However, I imagine through loading videos, YouTube can still collect some data. (I might be wrong though, I don't know exactly how much they pipe through their servers.)
If you want to be completely private, you'll probably have to use TOR together with those alternative clients.
If you want to be completely private, you'll probably have to use TOR together with those alternative clients.