First of all, don’t waste your precious time enjoying life with privacy worrying and fear. It’s just not worth it.

I don’t know why, but I get the impression the device you are struggling to make more private is a phone. If that’s the case, the extent to which you can make things work is indeed very limited, so don’t try to push it too hard.

You could use a tool like a firewall to have a more high-level control over all apps, like blocking them all and only allowing a few.

This may be less overwhelming than trying to block and contain each app individually. Now, you will still need to allow some Google stuff to have a Google phone work properly (to use the Play Store for example). If you want to go further, I’d suggest trying another OS other than Android, but that may make your phone even less compatible with what you are relying on, so it may be a better idea to instead try it on an old phone first.

On a PC, you have more freedom. Instead of trying to block everything from Google, for instance, you can rely on a separate browser profile (or Firefox Containers if that’s inconvenient) for things that really need Google (e.g. Meet, work/school using Google Apps, whatever) and in your main browser profile you can rely on alternatives. For example, instead of trying to access YouTube behind a Google blocking extension, you could use Invidious or a dedicated app like FreeTube.

I hope you can feel more at ease with the sense of being watched and tracked online, but remember that’s not worth loosing your best moments for if it ends up just causing more distress to you.