Kind of. I don't use grapheneOS and I'd like to, but de-googling your phone by buying a Google phone seems a bit sketchy. I don't want to take away from a privacy focused project. I'm super thankful for this option and I can't stand android or iPhone. But in the back of my mind I wonder if I'm being tricked.

As for why graphene uses graphene uses pixels - their FAQ does a good job explaining. As for why google keeps the bootloader opened and maintains (until recently) good enough device-tree support- I would guess mostly historical reasons? Before becoming as mainstream as they are now nexus and pixel phones used to be in part android development devices and certain creature comforts stuck. This seems to be souring though, so some of the people there may be in talks with an OEM for a graphene os specific device[1].

[1]: https://discuss.grapheneos.org/d/23886-partnership-between-g...