Btw, I must also note that I've gotten some cool music recommendations from Youtube, despite having quite snobby and unusual tastes — mostly by the virtue of jealously curating my algo for years by not opening any random stuff under my account (usually using an incognito tab for that). I think it might also be possible to do that by just using the recs under videos.

Fun fact: Youtube tracks recommendations for a non-logged-in session. With the help of Firefox's ‘Multi-Account Containers’ that isolate a site in some tabs from normal cookies, I once ran a logged-out Youtube session for a month or two just to listen to some eurodance/europop tunes from my youth without polluting the main account.

So you could in fact have proper personalized recs without logging in, except for videos that are marked as adult or if using a VPN or Tor.