Is there any node command in GH like Rhino’s for selecting subsurfaces of polysurfaces, such as using a command like Ctrl+Shift to select subsurfaces in a polysurface?
You can get a list of the brep faces by using the Deconscruct Brep component.
You will need to determine some criteria to sort/select/group the faces (area, normal direction, location, connectivity, etc…).
-Kevin