Office has long been the special case inside Windows Update (or Microsoft Update in the years where the brand changed whether you had Office installed or not), since the earliest days of Windows Update. Windows Update started as Office Update in the Office 97 era before becoming an out-of-the-box Windows thing in Windows 98, as I recall it. (The internet doesn't seem to have images of the Office 97 "Office Update" tool, so either my memory is foggy or it truly was short-lived enough that the general internet and Wikipedia have forgotten it.) In Windows 8 and 10 Microsoft tried to move Office updates into the Store and were mostly successful just about the time that the Office team decided they were bored with the Store and moved back "home" to Windows Update (or Microsoft Update, I suppose, if you insist).

If Office is no longer the special case in Windows Update and more applications can use it, that would be interesting. A lot of third party drivers have already been using it more, and that also seemed a special case before. Opening it up as a platform for any third party seems like a long time coming.

(Visual Studio is an interesting case, too, because some of it has always had security updates in Windows Update, but yet more of it is not updated that way than is. Originally the border lines were "owned by Windows components" versus "Visual Studio owned components" but those lines have become so blurry, especially in the .NET 5+ era where Windows no longer owns anything about .NET, but Windows Update still serves critical security patches.)

Also, the App Store "policies" have been hugely relaxed for years and allow general Win32 apps with no more sandboxing than usual from any other way of installing the app.