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...
Note that I am a GrapheneOS supporter. You seem to have a few misconceptions.
GrapheneOS is one of, if not the most vocal organization against the abuse of attestation mechanisms. GrapheneOS and its userbase feel the consequences of play integrity every single day.
Im not sure where you got the idea that all GrapheneOS wants is to be accepted by play integrity, because that is not the case. GrapheneOS has been working with regulators to get play integrity banned. Being accepted by play integrity, but nothing else changing, is not good enough for GrapheneOS. It would only be a small victory along the path of abolishing this nonsense.
So, no, GrapheneOS and its community are definitely against play integrity. The "signs" that they are "starting to notice" are not there. They are already fully aware of what attestation is and how it can be abused. They are definitely not ignorant on the subject.
You might be confusing root based attestation with pinned attestation. Root based attestation is flimsy and allows tools like play integrity to ban operating systems they do not like. Pinned attestation, on the other hand, has real security properties and cannot be abused to block certain operating systems. GrapheneOS uses pinned attestation as a part of their Auditor app, and it has other cool uses we could see in the future.