GrapheneOS and others should have lobbyists or rather lawyers and lawmakers to fight for using secure systems to mandatory be allowed for these. Sure, there must be some type of OS guarantee, but that should not be exclusive to Google and Apple. And indeed browsers with otp/authn devices (not one per service but yubi/thetis type of thing as those can be made sovereign for a large part); when an OS is not allowed, the browser and app should be mandatory allowed with such a device as that is, actually, more secure than the original device as it is an external encryption and encryption key source the hacker cannot reach.