Accessing geomtry generated by Grasshopper via Rhino Plugin (C#)

I am trying to access the geometry generated by a GH document and sent via preview component to Rhino (the issue might be here), but whenever I call doc.Objects.GetObjectList(Rhino.DocObjects.ObjectType.AnyObject) it returns an empty list

Grashopper geometry is not doc object. Only baked geometry becomes part of doc. I have no idea is it possible to access Grasshopper geometry, while working outside of it. Maybe McNeel dev wizards could help. In theory it is somewhere in display pipeline…

I imagine prederred custom workflow with Grashopper geometry could be developing new component plugin or writing script inside of Grashopper definition.