Seeing the holes on the side, this would also be usable for crushing garlic, and maybe also other spices as well, before cooking them, to release their spice outside their shells. Mentioning that would make this tool more efficient.
Also, why not simply use a cheap garlic crusher instead? Seems like a multi-tool, in this case, as long as what you try to crush doesn't fit through the holes, which would lower it's efficiency but not make it completely inefficient.
Also, they probably have hammers, so why not simply make a metal cup, which to hold the nut onto the hammer while they strike the hammer onto something hard (a rock, an anvil, etc.)?