> In that case, OS access becomes moot.

Not really.

1. A non-Google OS can shut off background running access to Google apps, as well as supply Google apps with mock location data and other data

2. Google does other things to the OS that drive me nuts. Like allowing apps to restrict screenshots. I own the phone. If I want a screenshot, it should screenshot. This is not something for apps or Google to determine, and if the OS listens to me (not the app) it should allow screenshotting the display 100% of the time regardless of what the app cries about.

I agree and have moved mostly away from everything Google. But it's hard to replace maps. I know open street maps exists but it's hard to beat Google's data gathering.

Using Sandboxed Google Play doesn't defeat the purpose of using GrapheneOS and neither does using Google apps. It does not exist specifically to avoid Google apps or services. It exists to provide a highly private and secure OS retaining high usability and app compatibility. Being able to use sandboxed Google Play is an important part of what it provides. Many GrapheneOS users don't use it and many who do use it are only using it in a dedicated profile for a small subset of apps but that's not at all required to heavily benefit from GrapheneOS. Moving to more private apps/services over time does make sense but it isn't mandatory and users can choose what kind of compromises they wan to make.

What are some good alternatives