Cel shading + DOF and fog

I originally followed this guide on “semi cel-shading” and got really nice results, hower if I wanted anything like depth of field or volumetric fog it was all being banded and distorted by the cel-shaded post process and like this.
Essentially it works by using a post process material which effects anything with CustomDepth enabled.
Probably a silly question but what would I need to do to include effects like these with cel shading? I’ve seen this and this example which actually referenced the same guide I linked, and I essentially wanna know how it’s done.
Any assistance will be greatly appreciated, I’ve not touched upon post-processing as much as I’d like and this is all new for me.
Thanks!