I also have both Pixel and Daylight. The problem is not with the OS communicating with Google. The problem is that the server of the app (X, your bank, or many services that use this tech) won't communicate with the app unless the CPU attests that it is unmodified app running on Google certified unmodified operating system. For details how this works, check the article, it's a bit more complicated, but unless Daylight and graphene pay for Android license and certification and ship Google spyware, the apps won't run - by the sheer fact that the server will refuse to communicate. It's cryptographically secure unfortunately.