retrieve the public ssh key for the subkey handled by gpg
$ gpg –export-ssh-key mattia ssh-rsa <A_LOT_OF_STUFF_HERE> openpgp:0xA2E43D00" — https://gist.github.com/mcattarinussi/834fc4b641ff4572018d0c665e5a94d3#:~:text=Retrieve%20the%20public,A_LOT_OF_STUFF_HERE%3E%20openpgp%3A0xA2E43D00
$ gpg –export-ssh-key mattia ssh-rsa <A_LOT_OF_STUFF_HERE> openpgp:0xA2E43D00"
— https://gist.github.com/mcattarinussi/834fc4b641ff4572018d0c665e5a94d3#:~:text=Retrieve%20the%20public,A_LOT_OF_STUFF_HERE%3E%20openpgp%3A0xA2E43D00