In a word, no.
We had downloaded both the newest Windows 10 and latestest Windows 11 GPO Templates , “installed” them on a Domain Controller and copied the Windows 10 GPO Templates into the central store (in the usual location of C:\Windows\SYSVOL\sysvol\<YOUR DOMAIN HERE>\Policies\PolicyDefinitions ) when we noticed something odd about the Windows 11 Templates. There were a lot of them; 220 to be exact.
We knew that Windows 11 GPO Templates are NOT backwards compatible with Windows 10, which seems so very illogical to us given that Win11 is little more than Win10.1 under its ugly skin. As such we decided to confirm that Win11 GPO Templates can live happily with Win10 GPO Templates and we found this nasty quote:
What to do if you have a mixed environment of both client operating systems? Well, fact is that you can only copy one set of ADMX files to your Active Directory’s Central Store. Depending on what your future plans are, you should decide which templates fit best. If you plan to stay on Windows 10 for a while, you should choose the Windows 10 ADMX files. If you’re ready to upgrade to Windows 11 and this will become your dominating OS version (or it already is), you should copy the Windows 11 ADMX files to your Central Store.Helmut Wagensonner, Microsoft
In other words, which OS would you like to control, because you can only do one. Without further research, we have no idea how companies with more than a few computers are expected to migrate from Windows 10 to Windows 11. I can’t imagine a CTO or CSO approving having an OS with no GPO’s applied to it for the many months it takes large companies to transition to a Windows 11.
Off the top of our heads it appears that this is a way for Microsoft to drive InTune purchases, because InTune can handle both Windows 10 and Windows 11 policies at the same time, but that is going anger many.
Windows 10 and Windows 11 GPO Templates are incompatible? That is just crazy.