Hello,
It's already possible, provided you have the right SDK and call the compiler and linker "by hand" using the right flags. Not very user-friendly I admit.
The build script at the moment is too focused on iOS apps, even if I'm trying to change that there's still some way to go.
There's one thing the builder won't do at the moment: it's the compilation of .xib/.storyboard (Interface Builder) files. If your app uses none, it certainly can be built.
Do you have a templated example of such an app to share with me, so I can see what's needed to improve macOS support ?