Cameron White

If the props are part of the agent's geometry, I think you'd want to make sure you have a separate prop joint so that the shield can move independently from the hand joint when it separates.
Then if you want to drop the shield via the ragdoll solver, you could switch to a partial ragdoll state where the prop joint is active but the rest of the character is following your animation clip. If the prop joint is parented to other joints in the skeleton you would also need to remove the Bullet constraint that's holding it together in the ragdoll sim (this is basically the same idea as detaching limbs from a ragdoll https://www.sidefx.com/docs/houdini/crowds/ragdoll.html#detaching-limbs-advanced)

I think you need to also wire the heightfield into the third input of RBD Car Deform. The extra sphere collider also probably would need to be merged into the heightfield too, probably with HeightField Project?

The bug with displaying Cd on packed fragments is fixed for 20.5.348