Not sure if I'd use GrapheneOS even if it was available on other devices though. Really not a fan of the hostile attitude towards rooting when it's needed for basic functionality like backups — actual, reliable backups for every app, unlike those provided by the built-in solution.
> GrapheneOS is exclusive to Pixels because no other device has the same security features like bootloader relocking.
Sure, because they picked a set of features exclusive to Pixels. Nothing is stopping them from being more permissive about the security features they require.
I do understand why they chose to stick to Pixels; I think it was a mistake nonetheless.
Except for the fact that they don't want to be permissive to keep on being secure.