Applying physical properties to brep or mesh allowing it to fall to the floor

I’ve spent a good few days and weeks over the last year trawling the net for videos and tutorials trying to work out how to apply physics/properties to meshes and I’ve spent a good long while watching YouTube videos in other languages too.  All very helpful but I’m still not quite there.

Over that time I’ve discovered quite a few new techniques and points of interest to explore but I keep coming back to the fundamental issue – I’d like to give breps or meshes physical properties to allow them the fall and fill a vessel.

I’ve attached a simplified example of one problem.  I’ve broken a simple cuboid into fragments but I’d like the fragments to fall to the bottom of the vessel which constrains their movements and how they settle.

I keep coming back to this and I want to work it out in Grasshopper and not resort to Blender if I can help it.  https://youtu.be/rWbXfwTJQGA

Thanks in advance

Andy