Hi, this is done using the PKPass NFC Type... Using this, a pass in Passkit can emulate an NFC Card.
BUT: You can only use this with an NFC Pass Type Identifier or what it is called like. I am from germany and know skidata and their way of thinking and love it! This technology of using a pkpass is very nice - but you need that nfc certificate. And I assume, apple doesn't provide any of these anymore. I have already requested such in multiple projects - but never even got any response!
I'll contact apple support next days :)