Dunno about Apple's version but with Wine you can linnk native code against winelib, allowing you to test what you have already ported before you got everything up and running.
Of course if Vulkan was a suppoted API on macOS, developers could just port to Vulkan on Windows and then implement the rest on macOS.
Of course if Vulkan was a suppoted API on macOS, developers could just port to Vulkan on Windows and then implement the rest on macOS.