Each generation seems to add an additional part. I know they serialize Face ID module, maybe the screen, the battery gives an indicator in the settings menu tha

Each generation seems to add an additional part. I know they serialize Face ID module, maybe the screen, the battery gives an indicator in the settings menu that its not OEM but it still works. I doubt the case or volume buttons are tied to the phone but what else is left? The Antenna or USB-C port?