Technically Windows doesn't support Vulkan at all, but the openness of the win32 platform allowed Khronos to define a "backdoor" interface where the application ignores the Windows graphics stack and instead gets a Vulkan context by talking to the graphics driver directly. The UWP sandbox makes this impossible so you're stuck with the native Direct3D APIs.
Statistically, nobody actually builds real UWP apps, so it is largely an academic point. But if you're out of the sandbox, I fail to see a good reason not to just build a regular old Win32 app the way it has always been done.
If you are on Windows on ARM then there is no option other than UWP apps. Why would anyone buy an ARM laptop if they have to rely on emulation for everything anyway. It's not like the ARM laptops are any cheaper than the intel ones. (they actually have worse specs and cost more)
The Xbox One uses a variant of D3D12 and doesn't support Vulkan at all.