On May 9th, 2017 Microsoft release a CU for Windows Nano Server 2016, Since the release I’ve tested the build and I’m happy with it.
If you are a Nano Server Admin or just a fan, I suggest you give it a go and test it.
Below, you will see that only one update is available for my Nano Server.
Below, you can see my build number for updating my Nano Server
As you can see below the build number has changed.
To update Windows Nano Server 2016 visit the page below