GrapheneOS is very usable as a daily driver. Nearly every Android app can be used on it and there's a huge ecosystem of open source Android apps. You should read the whole linked article which explains in depth how someone new to using it set up their device. They chose a certain way of doing it to balance their priorities. Only a tiny portion of apps can't be used on GrapheneOS which are mostly a subset of around 15% of banking apps which ban using a non-Google-certified OS in a way we can't easily work around. Most banking apps do work and extremely very other apps are unavailable. Google apps and services aren't used by GrapheneOS by default but can be installed as regular sandboxed apps.

You don't need a Google account to use YouTube and can use it via the browser, NewPipe or several other alternatives rather than their app.

The linked article covers someone's first experience with it with a lot of detail. They're using it as their daily driver with mainly open source apps and separate profiles with mainstream apps they still need. They're using those with much better privacy protections including having sandboxed Google Play in those profiles for using mainstream apps rather than regular highly privileged Google Play heavily integrated into the OS and not running with the standard app sandbox or privileges.

Like others have said, you can use Youtube without Google account. Moreover, you can give Google the middle finger by using uBlock Origin or viewing though a third party client like VacuumTube. Also don't forget the shorts filter recently featured on HN to remove those annoying portrait format videos.

As someone who doesn't have a Google account, I can use YouTube just fine on my GrapheneOS phone using apps like NewPipe.

Why do I need a Google account for Youtube? It seems I can watch nearly any video I want without logging in. Moreover there are anonymity proxies like Invidious.