On the graphene website, I would recommend reading their full “Features” page. It explains a lot.

In addition also look at /e/os/ as well. I am currently de googling from my primary phone to a secondary phone (on my old phone; I flashed /e/os/ on it. And it have no Google apps. They have micro g integration built in. And I use “shelter” to create a work profile to isolate the apps that are not privacy focussed and they forever live in that sandbox, and you can turn off and on those apps with one click".) Changing my email address to govt/doctors/etc. And backing up data from google account is taking the longest before I disable that completely.