Developers have to go out of their way to implement triggering Play Integrity API checks in their app and then retrieve the results to check on their services. They're putting a lot of effort into banning anything not licensing Google Mobile Services. It's definitely not a security feature since it permits devices with no security updates for more than 8 years but not a far more secure OS than anything Google certifies. Google doesn't allow GrapheneOS to obtain certification and certification comes with highly anti-competitive rules which would be completely unacceptable. Their licensing system has been ruled illegal in South Korea and other countries should not only do the same but ban the Play Integrity API and other related anti-competitive features. These are not actual security features and that's an excuse for the actual purpose of enforcing their GMS licensing model including forcing including a bunch of Google apps with extremely privileged access and using their builds of many OS components shipped from the Play Store.