alt Hacker NewsGrapheneOS requires a locked bootloader and supports using deveice attestation via the generic attestation functionality in the Android Open Source Project.
Play integrity is an anticompetitive tool that ignores this, and artificially limits itself on GrapheneOS. It is not due to any incompatibility.
The GrapheneOS supporters are not on our sides, apparently. The seem to actually like remote attestation. They just don't like that they are not in on Play Integrity. But what is won if attestation includes official GrapheneOS releases but would still otherwise be exactly the same evil stuff that takes control of the user's device?
I still am hoping that at one point they understand the full consequences of remote attestation. There are some signs they start to notice, but it's slow...