Q: How can I use WMI to determine whether a machine is using Windows To Go?

A: The Win32_OperatingSystem class contains an attribute called PortableOperatingSystem that is set to TRUE if the operating system booted from an external USB device. You can therefore use this attribute to determine whether the operating system booted from external USB and is using Windows To Go. You can also use this information to create collections in solutions such as Configuration Manager.

WMI SELECT * FROM Win32_OperatingSystem WHERE PortableOperatingSystem=True

Or:

PS C:\WINDOWS\system32> WMIC Path Win32_OperatingSystem Get PortableOperatingSystem
PortableOperatingSystem
FALSE