Hey all, we're on Homebrew now. Try
brew install libgosu
to try it out. :)
https://github.com/Homebrew/homebrew-core/blob/master/Formula/libgosu.rb *hurray*
It should provide an alternative to CocoaPods for doing C++ work on macOS. Although I'm not sure how well it will work if you're interested in distributing your game beyond your own computer... If you figure that part out, let me know!
Is this something that would be good on the Getting Started on macOS page? Maybe? Maybe not?