Nginx + letsencrypt certs doubt

Is mandatory give access to letsencrypt cert .pem files to HA to access by nginx reverse proxy secured? If I add nginx host with no ssl I can access to HA from outside with my duckdns address through nginx host, only by http, not https, of course… But if I add the ssl opcion to the nginx host, I can’t access by http or https…

You should be able to access it using https:// and keeping the rest of the URL the same. If you can’t you need to check the NGINX logs.