You are not quite the owner on GrapheneOS either, because of Android Key Attestation (which has functionality analogous to desktop TPMs). If you re-unlock your bootloader (say, to run a custom build of GrapheneOS), attestation will snitch on you and the subset of apps that use key attestation to require a locked bootloader and/or enforce an AVB key allowlist will not work properly. This is a very small subset of apps currently, but I don't see it getting any smaller.

GrapheneOS does everything and more for key attestation, allowing security sensitive applications to test the integrity of the device. Sadly some apps like google wallet not only check for attestation, but check if Google's signed it. Which is against the idea of attestation in the first place.

So google's tap to pay doesn't work, but others do, like garmin pay. Random bank apps are hit and miss.

> GrapheneOS does everything and more for key attestation

Right, that's the problem, in my opinion. I'm not referring to the apps that require Google's keys only, I'm referring to the ones that allow GrapheneOS keys too. If you use one of these apps, you can use vanilla GrapheneOS builds, but you cannot run your own self-signed builds.

You are gaining freedom relative to running Google's OS, but you are still not free to further modify the software running on your own device.

Apps that require "integrity" should monitor their own integrity only, they should not attempt to infer the integrity of their environment.

Trick is there's no integrity without the OS. Cheats can ruin games, keyloggers can record passwords, music/movies can be stolen, bitcoins can be stolen, etc.

Attestation does not solve this.

You can never own a device with a cellular modem. They can all provide backdoor access regardless of the primary OS.

It is possible to build a device where the modem is not at all trusted, but I don't know if anyone is actually doing that.

The fewer devices doing it, the more effective it will be for those who do it.