Rendered Buffer and Depth Access

Hi,

I am new to unity but well versed with Dx11 architecture and graphics pipeline. I am looking to get an
access to the final rendered Color and depth buffer from rendered unity scenes. After going through some
documents I feel I could write a native C++ plugin to get the device and may be the final RTS and depth. Will this work ? What are the primary events to map which signal the end of scene render ?

Also it says to load a native plugin one needs to at least import one its functions in the C# script. Is it possible to developed an engine plugins which might work for all the scenes without the scripts ?.

Looking for pointers how to approach this.

Regards
VC