Creating Prims in Your Scene
As explained on the Primitive Types and Primitive Attributes guide, you can create various types of USD prims directly in Nuke.
Find out how to do this:
For geometry, see Creating Geometry Prims.
For scopes and Xforms, Creating Scope and Xform Prims.
For points clouds, see Creating Points Clouds.
For cameras, see Working with Cameras in the New 3D System.
For lights, see Light Your Scene.