Can Animation Nodes extract data from dupli-instances? By dupli-instances I mean dupli(verts/faces/particles/frames). I was thinking that once vertex snapping is working with duplies in 3d viewport, then you can somehow extract vertex location and poly's in Animation Nodes, like from normal mesh.

Is it possible or not?
I don't think the API provides such access. However, it is very easy to generate this information yourself based on the data already given by blender. For instance, vertex dupli-instances data can be generated as follows:



Similarly, we can do that for polygons, edges, particles, and frames.