[numpad0]

I think you're supposed to make a "Pass", load it on Wallet app, then load the card with double press of side button. You can't just tap a blank iPhone and get its raw hardware ID.

At least Suica train cards(based on FeliCa/NFC-F) on iOS can be read from third party Android apps, and Apple do advertise iPhone feature to store corporate IDs, so the idea of using iPhone for gate tap-in card should be completely fine.

[lxgr]

None of this is accessible to hobbyists, unfortunately – you'll need a special entitlement, certification, your use case to be an approved one etc.

It's not accessible to "regular" app developers in the way it is for Android.