Equivalent of PageExtensions.CreateViewController on Android

On iOS I'm able to inject Xamarin Forms into an existing Storyboard-based project by getting a UIViewController from a page by using:

                var viewController = Xamarin.Forms.PageExtensions.CreateViewController (page);

However, when looking through all of the Xamarin Forms samples on Android it seems like everything does SetPage using the AndroidActivity as the base. Does this mean that projects must at their base be Xamarin Forms on Android, or can we take existing projects and inject Xamarin Forms on Android too?