So I have a hybrid setup with Linux and Windows Server. I am doing DNS validation due to ISP and no port 80 access. I found a port for the ACME script in powershell and they wrote a plugin for DYNU. im going to try and get it working and post the results here. Feel free to help if you are better than I at powershell.

https://github.com/rmbolger/Posh-ACME/blob/master/Posh-ACME/DnsPlugins/Dynu-Readme.md

Did you ever get this working? Im in the same boat but when I try to use the dynu plugin i keep getting "The remote server returned an error: (401) Unauthorized."