Do you have a reference on graphene being affected by the app signing? I tried to find an answer earlier, and came up with nothing.

isnt that only in thier newer and future models, im using the 12r, and you can still unlock it, im not saavy enough to change the OS.

The phone would be shipping with GrapheneOS, you don't need to unlock the bootloader if you are the OEM installing the OS.

/

We kind of know part of the answer. They want to be able to re-lock the bootloader. they also want to be able to use as new a version of Android as possible.

Eh not really, in India you can get a 2nd hand Pixel "a" model a couple years old and have it last for nearly a decade with official support and GrapheneOS extended support, not bad value for money but certainly a bit more expensive than the most budget phones.