Dumb idea, but I wonder if the underlying os can see who is asking questions like do you have root, And if an app has no need to know, it just plays dumb and responds...of course not. It's a bit of a chicken and egg problem, in that if you don't know what apps need to know if you have root, or not, then you can't determine that at the OS level...maybe an option for the user (popup) to tell the program, tell them we are rooted or not? (Or a settings page you can determine what apps can know root or not)
perhaps but this is about device/os attestation, not rooting
That's exactly how modern Android rooting tools work. You select which apps you want to have root, in a manager app. No other app should be able to notice.
But GrapheneOS isn't root, that's just PayPal's thing being broken.