Face id not working/possible fix?

This would be a microsoldering job. The pairing is done via hardware and I've never been successful at tricking the software.

Starting with the iPhone 12 series, Apple has relented somewhat with their parts pairing, allowing you to replace components that were previously not easy to replace due to pairing issues. As of iOS 18 and later, there is a new utility, the Repair Assistant, that runs when a part has been replaced. The caveat here is that you can, of course, only use genuine Apple parts, but they can be either new or used, as long as the used part doesn't come from a phone that's been reported lost or stolen.

I can't answer this definitively, but I've seen at least one report that the Repair Assistant will work with Face ID components, which would be a boon to us if that's true. So you should be able to go on the Apple self service parts site and purchase your new front camera assembly, in which case it's a pretty safe bet that it'll fix your Face ID issue, or you can look on places like eBay for used parts that will also work, as long as it's a genuine Apple part.

"Face ID disabled" means the communication with required Face ID components failed or pairing does not match, therefore the OS refuses to turn it on. It's not like damages limited to the lens part of the projector or bent module frame, in which case the Face ID will turn on normally but always ask you to move your head then fail to scan.

The dot projector comes with both software/hardware and physical personalization, so it is only possible to replace the Face ID module as a calibrated and personalized set.

Due to the one-time-only personalization, it is not possible to reuse another set taken from another iphone for this model, Apple sells brand new set via their self service repair program that can be paired to the phone normally.