Creating a custom renderer in Xamarin.Forms manually

Is there any way to create a cutom renderer and retrieve the native control manually ?
For example:

//Example on android
var frame = Element as Frame;
var renderer = new FrameRenderer(){Element = frame};
renderer.StartRendering();
var nativeControl = renderer.GetControl();
bool result = typeof(nativeControl) == typeof(ViewGroup) //true

Of cource this is all imaginary but it illustrates what I want to achieve.