I have been quite happy with the Gtk bindings for Go (https://github.com/gotk3/gotk3). As Gtk has a C Api, it is a good match for Go, actually Go makes Gtk nicer than calling it from C in my eyes, as the GObject wrap to Go types and you can just call methods on them vs. the C syntax of passing the GObject as the first function argument and having the object type in the function name.

If you install the Gtk libraries on the Mac, Go programs written with gotk3 just compile and run there too.