Nitrokey 3 gpg "keytocard" asks for admin pin that's never been set

That thus makes me unable to move the new secret key I generated to the device. I’ve tried an empty password, didn’t work. I did a gpg factory reset for the device, didn’t work. What key is it asking for?

I think it sets to a default value like: 12345678

It is best to change it.

Huh, you’re right. I didn’t see that anywhere in the docs… Thanks!

Now to find how to change that pin…

You need to run gpg --card-edit and within its shell run the commands admin and passwd.
You should also change the PIN.