At least with an Android i have the option of Graphene, and have access to a terminal, and for now can sideload apps.
With apple there's no choices, so I'll continue to take my chances with Android
Can Graphene OS pass this kind of Google attestation challenge, though?
Possibly... but the extension of this to Android and Apple is going to be the entire internet shuts you out. And everything else will be a giant Dead Internet crawling with bots.