Fog of war effect in visionOS

We performed spatial mapping using the plane manager and covered the mesh. However, due to the rendering scope of the plane manager, no mesh is applied to the non-rendered real environment.
I want to cover the space that is not covered by a mesh, but I understand that visionOS does not support post-processing and scripting shaders. They said I could use shader graph, so I looked for a way to do it, but I couldn’t implement it. I would really appreciate your help.
image

Is there a way in visionOS to implement this effect in real space like in a photo?

I summarized the questions and re-posted them at that link!