Letsencrypt & Duckdns still work together?

For years I used this combination. Currently I moved from RPI to Odroid and can not get this secure access method to work. Nabu Casa entry works. I read the Letsencrypt documentation and they no longer list Duckdns as supported. Is that right? No more Letsencrypt/Duckdns for security? Thank you to anyone that can provide some clarity, Doug