Q. What is the easiest way to create the unattend.xml file to be used with the creation of a Nano Server VM?
A. The best way is to use the Windows System Image Manager that is part of the Windows 10 Windows Assessment and Deployment Kit (Windows ADK) and available from https://msdn.microsoft.com/en-us/windows/hardware/dn913721.aspx. Once you have installed the Windows ADK (you only need the Deployment Tools group) launch the Windows System Image Manager and load in the NanoServer.wim from the Windows Server 2016 media. Next create a new unattend answer file. You can now drag components to the unattend answer file. For example under Components select Microsoft-Windows-Shell-Setup and drag it do the specialize Components of the unattend. You can then select the component under unattend and fill in data for the required settings, for example TimeZone as shown. Make all the required configurations then save the unattend answer file.
This is then usable as part of the New-NanoServerImage cmdlet via the -UnattendPath parameter.