Sort of. If you're OK with manually updating the certificates after initially fetching them from L.E., then you can use them. However L.E. must be able to commu

Sort of. If you're OK with manually updating the certificates after initially fetching them from L.E., then you can use them. However L.E. must be able to communicate directly with the server via HTTP to prove authority and send you the certificate. There are other tests that the ACME protocol can do to determine authority over a domain name, but Ponzu's implementation doesn't handle them. Sorry if that doesn't fully answer your question.