Google certification isn't open to us due to requiring licensing Google Mobile Services and agreeing to an enormous amount of anti-competitive terms including banning many of the privacy and security features we provide. It would also be incompatible with providing updates without unacceptable delays.
Play Integrity API is disguised as a security feature and is aligned with governments wanting to crack down on people freely using arbitrary software and hardware which makes it hard to convince governments to stop it.
Potato, potato, right?
Is there such a thing as a non-stock operating system that is certified by Google?
This is excellent news, because the phone that has been confirmed so far (the Signature 27) is absurdly large and expensive. The Pixel 9 I currently run Graphene on is already too big for my taste.