It’s the exact same command as a regular SSH prompt and it generates and uses the cert. that seems very simple.
Your command is disingenuous in that it only works if the certificate has already been issued to you. If you were to include issuance, your command would very much turn non-simple.
If I'm reading it right then there's a non-insignificant amount of setup necessary for the proposed approach anyway, generating and sharing a public key is much easier even for the customer/client.
Your command is disingenuous in that it only works if the certificate has already been issued to you. If you were to include issuance, your command would very much turn non-simple.