Hi and Welcome to the Community,
Although not an expert in this domain, I’d rather attempt to work this through a node material (NME) post-process. Changing the materials and renderingGroup based on camera input sounds like something that’s very heavy (both to create and implement). Playing around with these parts will also create issues in performance and artefacts.
I’d suggest you have a first look at this post:
I believe the base of this FX created by (guru 
) @PatrickRyan can probably be revamped and twisted/enhanced to match your needs 
. There’s a part in his last post around ‘masking’ where I think I did read he was thinking of adding it to the docs, but I couldn’t find it?! May be I didn’t look close enough 
There will aso be a part around the camera and the ‘focus’ on object selection so it’s probably not the easiest thing to do (but then, if it was, why would need the expert? 
)
Now that I called in our expert on this topic (which I believe should be of Interest for him to take as a challenge ), I’d suggest you wait for his answer (and always to the point analyses). Better than venturing into something that might just be completely inadequate 
Might need a bit of patience though since it’s the weekend 
… Meanwhile, again, welcome to our Forum and have a great weekend 