Parent mentioned not using the Play Store or the Apple Store. The hardware Graphene runs on is kind of irrelevant for that. I don't see a problem with paying Google for hardware that I am free to use as I like; unlike other manufacturers the bootloader is unlockable, which means the stock OS can be replaced.

Requiring a device from the same manufacturer as the OS as the only way to be free: there is really nothing you see contradictive in that? I mean, power to you!