Apologies for the delay. We're working to post the NuGet packages on NuGet.org as soon as possible (hopefully just a few days). In the meantime, the setup (.vsix) is effectively a zip file that also contains all the NuGet packages. You could download from the ArcGIS for Developers site, unzip and reference those packages as a local NuGet source.
The packages have now been uploaded to NuGet.org. Apologies for the delay.
We're also interested to hear what further support you would like to see for Xamarin Studio / Visual Studio for Mac. For example, an extension experience equivalent to that available for Visual Studio on Windows?
Excellent, thanks for the update.
We have been pleased with the support for Xamarin Studio. In fact we do most of our development on the Mac side for iOS and Android, and typically only use Visual Studio in Windows for testing the UWP app and implemented platform specific code.
We will certainly post if something comes to mind as we migrate over to the latest release.