What’s the challenge with getting it working in macOS? Vulkan?

They're not using a library like SDL for windowing and input as far as I can tell. All the MacOS interfaces are in Objective-C or Swift, which I would wager (I've never used Go fwiw) aren't as easy to bind to from Go code.

MoltenVK has some extra interfaces you need to integrate with too, it's not a completely hands off setup.