If you find yourself in a situation where you might be detained and thereby unable to control interactions with your device, on iPhone you can disable TouchID and FaceID by holding one of the volume buttons and the sleep/wake button simultaneously for a few seconds. This will require you to enter your passcode the next time you want to unlock iPhone. Anyone have similar instructions for Android?
Be very careful taking this advice. If you weren't already aware, the past week should make it crystal clear that police have absolutely no problem arresting or assaulting you for exercising your rights.