Is there anything about GrapheneOS that limits it to only Pixel devices, or was it just a prioritization decision?
It is sus as heck and just about everyone in cybersec was complaining about that weird decision.
Go for Calyx or any other android distro, they have zero difficulties in supporting more devices.
Yes. There aren't many Android smartphones that allow you to re-lock the bootloader after installing a custom operating system. Pixels are the only ones officially supporting `avb_custom_key`.
https://grapheneos.org/faq#future-devices