Convert .obj meshes to .usd, and add Semantic labels in Python

Hi, I would like to import ShapeNet meshes to a scene in Isaac Sim and use them for grasping task. However, the ShapeNet meshes have .obj format. So, I need to first convert meshes to .usd, then add rigid body and collision properties, and finally add the semantic labels. I can add rigid body and collision to the converted objects in python by:

But, I do not know how to do this convertion from .obj to .usd, and add semantic label to the object in python (I know how to do that using UI, but I need to do that in python).

It would be great if you could help me to solve this problem. Thank you.