FORTI (EXTERNAL) $ config system admin

FORTI (admin) $ edit "foobar"

FORTI (foobar) $ set ssh-public-key1 "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIEkNwIWR0Rqh1OLcYzkUuXWWqHynHtm47GAMTnOPoFLP"
SSH key is good.

FORTI (foobar) $ next

FORTI (admin) $ end

FORTI (EXTERNAL) $