My only concern is this: Android phones I tried to root so far will be "tainted" if I unlock the bootloader and can never go back to a state where it passes all checks.
I'm okay with losing access to Google wallet while using Graphene os (I can just use plain old credit cards), but I would like to have the option to revert it in the future.
Where are you getting this information? For what it is worth, Wikipedia mentions the Pixel 6 on the eFuse page https://en.wikipedia.org/wiki/EFuse
Myself I have not reverse engineered the Titan M2 security chip, but surely it uses eFuse or OTP memory for anti rollback protection mechanisms and such.
These are really basic hardware security primitives. I'm curious why you're under the impression Pixels wouldn't use eFuse.
You mentioned devices being irreversibly "tainted" after unlocking the bootloader.
On Samsung devices, blowing the Knox eFuse permanently disables features tied to Knox (e.g. Samsung Pay, Secure Folder). ("can never go back to a state where it passes all checks")
Pixels do not have an equivalent eFuse that permanently disables features (discounting the ability to flash previous versions of Android). Restoring stock firmware and relocking the bootloader will give you a normal Pixel.
The Pixel 6 is only mentioned in regards to anti-rollback protection. This has nothing to do with unlocking and later relocking the bootloader. Pixels have always supported relocking the bootloader with a custom root of trust, i.e. custom AVB signing keys used by a custom, user-installed operating system.
The Pixel 6 is mentioned specifically about eFuses which is the technical detail that caught my attention in this thread.
> The Xbox 360, Nintendo Switch, Pixel 6 and Samsung Galaxy S22 are known for using eFuses this way.[8]
Anti-rollback protection is a security feature, eFuses are hardware primitives that can be used to implement it. Bootloader locking is another security feature that can be implemented with eFuses.
If you have any data denying the use of eFuses in the Pixel 6, please share it, that is what I was interested in this sub-thread. I really did not understand the relevance and the correctness of your comment.
I'm okay with losing access to Google wallet while using Graphene os (I can just use plain old credit cards), but I would like to have the option to revert it in the future.