Android & iOS support via Xamarin

Does Xenko support Android & iOS via Xamarin? If so, then can I build a normal Xamarin app with Xamarin.Forms and activate Xenko only on certain screens?

I need to build a cross-platform mobile app which has a 3D earth view similar to Google Earth. However I need the UI capabilities of Xamarin, so I will need to combine Xenko + Xamarin somehow. Is this possible?

Yes, it supports Xamarin, but only in theory. The fact of using it in applications I have not met yet…