Unity scene search contrast effect

Hello,

I would like to achieve a result similar to when you search for an object in the hierarchy, and then in the scene window everything that is found retains its color but everything else turns into a white gray scale:
Example image

Ideally, this effect should not be screen space but I would like to create a looking glass through which the image looks like it: most of the objects would be gray-scale, and some special objects would retain their color.

Any ideas on how to achieve this effect? Should this post be made in the shader forum or the general graphics forum instead?

Any help is much appreciated!

Thank you

 

Anyone? Is this the right subforum?

Thanks!