Please ignore this post. I just can’t delete it. Is irrelevant.
If one might come across this, the answer is no and yes.
- No, you can’t put the main private key on the card, any PGP card not just the Purism one, they are not designed like that. You can only put the private subkeys. The main private key stays offline. Do I think that ok? No. But then again if smarter people said that’s how it should be done then that’s how I will do it ¯\ _ (ツ)_/¯
- Yes if you have a private key you can derive the public key from that, the same private key will always give the same public key. In the context of main public keys and sub public keys, you will want the public key of your main key. The public keys for the subkeys are irrelevant.