3D object to create a camera cutout

Hello, I guess I'm in the right forum to ask that question.

So basically we would like to create a cutout through every objects present in the scene using an other 3D object for a specific camera. The result will be that the camera will see his background color through the 3D object. It's to simulate in 3D what Blender can do with his View Layers feature to "render separately into layers to composite them back together afterwards"

View Layers — Blender Manual

Here is an example of what we need. Here the sphere and the cylinder are used to create a cut out. Than we could change the color of the sphere and the cylinder and overlap two (or more) videos or screenshots of the game to get different composition.

Does someone have an idea? Something like applying a shader to the sphere and cylinder and playing with layers to create the movies/screenshots. Is that possible?

Thanks for your help!