onigino okay, I think we might have been talking about different things. It sounded to me as if you wanted to update 3rd party apps via the GrapheneOS App Store instead of Play Store, now I get what you mean.
I didn't even know it was required to have the Play Store enabled to update Play Services, that indeed seems weird. Maybe I'm hallucinating, but I think when I was back on GOS I even uninstalled Play Store in a profile without issues. Would be interesting to see if that works (only try that in a separate testing profile).