Where is Omniverse PhysX API documentation?

As shown in the Python source code of Physics Demo Scenes, the code imports omni.physx related API, such as “from omni.physx.scripts import …”

I searched Kit Programming Manual, did not find PhysX related API documentation. I only found PhysicsSchema topics in pxr package, which I do not think it is PhysX 5 documentation.

My goal is to learn implementing the “soft contact” effect in Omniverse, which was made possible using Contact Modification as described in PhysX 4.1 SDK documentation

Please suggest where is the Omniverse PhysX documentation.

At the time being the primary way to talk to PhysX in Omniverse is via USD interfaces. These can be created in the e.g. Create UI documented here: Physics — Omniverse Create documentation
There is USD physics documentation here: USD Documentation : Rigid Body Physics in USD Proposal
Physics related python commands are documented in Help → Physics Scripting Manual. (In older builds this is perhaps still under Window->Physics)

Note however that advanced PhysX features like contact modification are so far not exposed in Omniverse Physics, unfortunately, so I am afraid you will not be able to access this effect right now. Contact Modification is on our TODO list to expose.