I know this is a bit offtopic, but on e621(warning: furry site) there is a userscript called Re621 that in the absence of a ‘subscription’ system allows you to subscribe and creates a kind of notification within the page that notifies you when an artist you subscribed to uploads new art, without the need for an account. Something like this would be ABSOLUTELY GREAT if it existed for Youtube, because I could just export my subscriptions and that’s it, if I format my PC I don’t lose my recommendations.

Since I can’t really help and I don’t know if something like this exists for Youtube, I wish it does because I also use Youtube without an account, but something I can suggest you is to use some instance of Piped and create an account (not related to Youtube, it only exists inside the instance) to be able to subscribe and save playlists, but only that in your case, because you will lose the personalized recommendations, you can also use FreeTube and subscribe locally to your favorite content creators there and export it as a backup so that if you were to format your PC, you can remember the names of the content creators to which you were subscribed.