As I understand the desktop version of Windows 10 ARM on the Raspberry Pi 3B has only been taken as far as getting a working system, that does correctly run, though with only drivers for framebuffer display and keyboard (not even mouse support yet).
There is no reason someone could not get it to working, if they are willing to get all the needed drivers implemented. Though running most applications would be a bit slow, as most Windows applications are closed source compiled for the x86, so would be running under emulation, though for the applications that you can recompile to be ARM native it would be fun to play with (just do not give it an internet connection, it is Windows 10).
If you want to put that much work into it though I would recommend seeing about getting ReactOS running on the Raspberry Pi 2b/3B instead. ReactOS still gives you the full Win32 API, and is closer to being open source (it is GPL, which really is more of a shared source license). You would have to add some kind of x86 emulation core for using applications that are x86 only (like Windows 10 ARM has), and of course you would need to get it working with all of the hardware. Though it would be more rewording than just getting a closed source OS running.
The Raspberry Pi is an ARM computer, that runs many Operating Systems, including Linux, RISC OS, BSD, Pi64, CP/M as well as many more.
Soon to add AROS to the list of operating systems.