There are documented values for Windows Vista to 10. The first Insider build of Windows 11 was just released, and the documentation wasn't updated yet, but perhaps it can be found somewhere in the system.
4 Answers
After a bit of fiddling around, seems like the current answer (at least for build 22000.51) is that there's no GUID yet. I found the list of GUIDs in ntdll.dll under the symbol SbSupportedOsList, referenced by a function called SbGetContextDetailsByVersion. The list contains only the five GUIDs mentioned in the documentation.
Microsoft says
... The following GUIDs correspond with the indicated operating systems: {8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a} -> Windows 10, Windows 11, Windows Server 2016, Windows Server 2019 and Windows Server 2022 ...
There is no new supportedOS manifest because Microsoft decided to keep the 10.0 version number. The supportedOS manifest for Windows 10 will continue to expose the current build number; 21996 and up can be assumed to be Windows 11.
have a look at https://github.com/MicrosoftDocs/win32/blob/docs/desktop-src/SbsCs/application-manifests.md#application
you use the windows 10 guide for >= windows 10, and >= server 2016
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