Canardo_Sanchez
I agree on what you just said. Personally, the OEM that I see this doing most realistically is still Motorola. While I do understand that every company likes to have their data harvested, Motorola ''only'' uses a slightly modified version of the stock os.
It's very different from OEMs like Samsung, the ColorOS trio etc - all of these add alot of their own apps, force you into logging into their accounts.. you know the drill. Motorola differs and seemingly only cares about the hardware sales. Their update policy isn't great and just to say this; im not affiliated or something and only a happy Graoheneuser that's throwing out thoughts in bad English :)
Motorola could make a phone with a chip that (mostly??) supports the security features GrapheneOS wants, and then sell this as a normal phone with play services and the second option could be something like ''No Google Services'' or just ''GrapheneOS''.
This is a naming sheme most people would understand and Lenovo already does this with their handhelds and some laptops: allowing the users to choose which OS they want. I reckon that the upfront cost/investment cost of this would be significantly lower (edit:) instead of creating a GrapheneOS-only device. There could be a FAQ or a 'Help me decide' section that mentions the advantages and disadvantages of using Graphene.
The main issue I see is that Motorola (or any other OEM)? must find some way to let the GrapheneOS developers do their job in a trusted way - the last thing any company wants is letting third parties ruin their reputation. Still, I think that this could be overcome by adding a warning that says this OS has nothing to do with Motorola.