If you quit YouTube then you also quit all the content on YouTube that isn’t elsewhere. The best solution if you still want to use it is to use 3rd party apps. Personally I would actually count that as having no reliance on Google in particular anymore. If a video platform owned by Google wasn’t the most popular then it would be another platform. I don’t think you should think of 3rd party apps as YouTube frontends, but rather, apps that scrape videos hosted on Google’s servers.
in my opinion, it’s up to you. there shouldn’t really be a strict definition, since everyone’s needs and starting point is different. don’t worry so much about trying to live up to a particular standard and figure out what level and methods of disengaging from Google (or any other tech company) works best for you.
(edit: autocorrect fix)