Camera trickery magick trick cool thingie?

So I got a cool idea but I am not sure if this is possible with blueprins…

Can I somehow set the camera to only capture specyfic objects?
To specify:
What I want is NOT setting objects as not visible for a specyfic camera.
What I want is to only capture the flaged objects and output the rest of the FoV as alpha.

Then I want to add what multiple of those cameras see as ‘layers’ in the viewport (kind of like layers in Photoshop, Krita, Gimp, u name it). That would let me have diferet FoV and diferent postprocesing on different objects in the scene which would be incredibly powerful for highly artistic scenes.