RFC2136 DNS validation support
To implement RFC2136 you'd generally call nsupdate, so the simplest thing to do is just use your own .bat file, https://www.win-acme.com/reference/plugins/validation/dns/script
This looks like it could be interesting to add as a plugin, though I'm not familiar enough with the technology to estimate how difficult it would be. If anyone knows a good .NET implementation of RFC2136 as a reference that would be helpful.
I ended up using rmbolger/Posh-ACME. Very easy to setup and to deploy on Windows server services with rmbolger/Posh-ACME.Deploy
This project appears to have implemented RFC2136: https://github.com/alexreinert/ARSoft.Tools.Net
Sadly, I think that ARSoft project is basically abandoned. I had looked into it when I was first trying to write the Posh-ACME plugin for RFC2136. But if I recall correctly, it's .NET Framework only, no Core support. There are a number of years old unanswered PRs including one to target netstandard 2.0. It's possible someone might have forked it by now.
The libary is alive again but now we're blocked on https://github.com/jstedfast/MimeKit/issues/865
Beta released in 2.2.4