@Xeniax I used Graphene for months as my main OS and still consider going back to it, but default to iOS for security. Quick points:
-Have a clear vision of what problem you're trying to solve by using GrapheneOS. If you install Graphene but don't change some other habits that may be related, its utility will be limited.
-Graphene is mostly viable, but certain apps simply won't work as they require validations that Graphene won't/can't pass. Mostly bank and other finance apps, but also Hulu.
@Xeniax
-Google Play Services vs. alternative app stores like F-droid have benefits and drawbacks. In particular, F-droid's signing mechanism has drawn criticism (including from outfits like Signal).
-One of the strongest controls I've instituted is using private DNS so I can see and control a lot of the calls the phone makes. Easy to set up with a service like NextDNS, but can also roll your own.
-If DNS feels a bit too far, check out PCAPDroid as it can provide some separate functions.