The solution to this is simple, the device could cryptographically verify the parts in it and if it detects a 3rd party part then on boot it shows a message saying "An unofficial touchscreen is installed" then the user knows if the touchscreen is working shit its probably because of that and if you sell the device the buyer knows what they are getting.
This is already the case. TouchID will disable on a device with a screen that is not re-keyed. Your solution isn't simple at all because it doesn't actually address the problem.
It does. Touch ID is just disabled and a message pops up saying that the display key doesn't match the Secure Enclave and that Touch ID has been disabled.
