How do you reconcile that position with what Graphene OS lists as requirements for support, as linked by another commenter? https://grapheneos.org/faq#future-devices

I’m not an expert, but all the listed points there sound reasonable. If indeed only the Pixels support them, well, it’s too bad there’s not other, similarly secure hardware out there.

Please go read this and try again: https://grapheneos.org/faq#future-devices

If you want Graphene level security you need to have the hardware for it.