How do I find out the local space to geometry space transformation within a geometry node? An example:
A box node is transformed through a couple of transformation nodes and connected to a null node. If i grab the null node, how do I find the transformation matrix of the box node (i.e. the total transform matrix)?
There's no notion of a “geometry space transform” that applies to the entire geometry. Each surface operator node directly manipulates/modifies/deforms the point positions. Now, if you wanted to obtain the object transform, that you can do. Search for OBJ_Node.