This is just a question of money, so, if you do have the financial capacity for the Pixel 10, go for it, it'll beat the other phones in terms of what you want from it.
Otherwise go for the Pixel 10a, but do note that support for it is still in early stages and might be somewhat buggy (less and less likely as time goes on, though, so take that comment with a spoonful of salt).
Other than that, the devices shall run GrapheneOS just fine, but do note that, for your use-case, the alternatives may be slightly subpar...