Hi there @Pilot_Life!
From what I understand they might request proof that you’re a legal resident, as the PostIdent option is really only meant for residents. But you could always try to go there with just your passport, but I wouldn’t get my hopes up for it working.
I believe they will take a copy of your ID and probably verify its authenticity on the backend.
In any case it would be interesting for the community to know if it works or not, so if you try, it would be great if you report back here! The worst thing that can happen is that they refuse.