That would be nice but I do wonder how much the Graphene project is going to be involved in hardware decisions if it is a major OEM. Sounds like it'll be more just a phone where the OEM provides support of bootloader unlocks and installation of graphene

batteries and hardware (motherboards, cameras, etc) on most phones and laptops are achievably replaceable. not "I'm boarding a plane better change it in my lap" but like half an hour of work, which isn't that big of a drag every year or so. watch any youtube video tutorial to get a better sense. I'm not saying grams can pull it off, but if you're even tangentially tech literate, it's doable.