> The whole point of Graphene is to have a fully locked down OS that still works as it should.

Not at all. The reasons I use GrapheneOS:

- Better security than other alternatives, even with the Play Services. A lot of hardened stuff, very quick updates.

- Play Services run in the sandbox, in terms of privacy that's not worse than microg, but I find it more convenient (I used both)

- More control over the app permissions, notion of "scopes", etc.