I haven’t looked at the OpenBSD code but have built a system that uses a separate server to actually perform the certbot http challenge. The server needing the

I haven’t looked at the OpenBSD code but have built a system that uses a separate server to actually perform the certbot http challenge. The server needing the certificate just forwards the port 80 acme requests to the certbot server CSRs were sufficient for that, at no point was it necessary to ship private keys. And this was using just the standard ubuntu certbot for the actual requests.