Iterative Closest Point (ICP) overlapping ratio with open3d

Question

I want to cacul the overlapping ratio between two point cloud. The idea is to create small equal box form the Aligned Bounding Box of the point cloud. Then calculate how much point there is in each small box. After this implementation for the two Differents Points Cloud, we compare all the same small box of the two Differents Points Cloud, then we make a ratio to have the overlaping ratio. My problem is to vizualize the sub boxes of each points clouds because i create them in a list since there is a lot of them. The Open 3d vizualizer problem is that i can't add a box on a curent vizualisation because it's in a list. Do you have an solution? I let you my code to try it.