My Linux server does not allow SSH login with password because I have /etc/ssh/sshd_config with "PasswordAuthentication no". I'm not going to be allowed to change that. It's fine and convenient for SSH access as it forces me to set up authorized_keys, which are so convenient once you set them up. So they're set up and my Mac can SSH to my Linux server with no password, np.
However I just set up netatalk to have an AFP volume. The login for the AFP volume via netatalk is the SSH username:password. So theoretically you'd think it would support the same public key login that SSH supports as well. But Mac Finder always asks for a password. My mount_afp command doesn't seem to work. "open afp ..." just opens Finder anyway. None of these in this MacWork Link seem to work without a password.
This differs from Automatically mount AFP for Time Machine (without saving a password in plaintext) in that that answer has the server using a password, but then the Mac side pulls that password directly from the keychain.