Rendering in a closed room

So I newbie to Blender but for my first real project without a tutorial, I was going to do an isometric rendering of my room. I’ve seen how you can have part of a room not show up in the render but still influence the lighting of the scene. I wanted to do that but every attempt I’ve made has failed. Does anyone have ideas? Thank you

Either turn off camera visibility for the objects, or (if single plane), use nodes to make them see through (camera only) from a single side (like, camera invisible from above, but visible from below).

Could you further explain how to do it with nodes? But anyway, thank you, that helps a lot