Search notes:

Registry: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SDKs\Windows\_version

Values for _version I've seen include v7.0A, v8.0A, v8.1A or v10.0.
Values I've fund under _version = V10.0 are:
InstallationFolder C:\Program Files (x86)\Windows Kits\10\
ProductName Microsoft Windows SDK for Windows 10.0.19041
ProductVersion 10.0.19041

Index