I was just watching the latest Xamarin Show with James Montemagno and was pleasantly surprised to see that Xamarin.Forms 2.4.0 Service Release 2 (September, 2017) added support for Mac Desktop apps. Of course, you have to use Visual Studio for the Mac, but that's completely understandable. In this episode, David Ortinau showed the gallery sample app running as a Mac desktop app. Very very cool.
They also made performance improvements by tightening up the number of UI layers required for basic controls. These improvements are especially noticeable with lists.
On top of that, they announced support for .NET Standard 2.0 (and therefore lower)
These features are new. Think of them as alpha.