Okay, help me understand what I am doing wrong then, because I am not getting that "Punchy" look when using AgX (OCIO View set to Punchy).
From what I know, RGB values (non-linear) for the brightest whites should be at rgb ~234 max, and rgb ~30 for the darkest blacks, that is for the brightest and ...

This also goes against the purpose of OCIO. Doing so will break the imagery.
It would break if I would bake it/export it with LUT applied, but that's not the idea. The idea is to only use that LUT for LiveViewer/IPR while look dev'ing. No? Reason why I'm asking this- I really like AgX's look/how ...

While trying out these new workflows a few new questions came to my mind:
1. Is it possible to use LUTs on top when using OCIO? Maybe some custom one, so the LiveViewer/IPR better represents what I'll be getting after the PP
2. What's the difference between Response and LUT? To me it looks like they ...

I see. So which path/method did you end up choosing? and why?

Well, yeah, that's obvious. But now for example I decided that default AgX highlights compensation/compression is too much or too less for me- the only solution to adjust that is PP in an external app, correct?

What you exactly want to do ? If only compensate, compress highlights - just use camera highlight compensating

BTW, what do you exactly mean by this? If you're talking about "Highlight Compression" in the Camera Imager, it doesn't work when using OCIO (Both ACES and AgX)
https://i.imgur.com ...

If I want to do some more serious PP/compositing etc, for example. For that I'd use Fusion, so I'm wondering what would be the exact steps for that workflow

Yes, ACES workflow here is just for example/for comparing, because I am familiar with that one.

I'd guess it should go like this (when using AgX):
1. Import the image
2. Do the PP
3. Convert from Linear BT.709 to sRGB:Punchy

But I'm not sure, would like to get a confirmation

So I guess the correct way of asking would be if it's linear or non-linear, right?
Anyways, I got my answer. Thanks.

The steps are as follow: an EXR 16-bit beauty (linear) export, plugged to an OCIO node in Fusion with AgX loaded and set to Input source: Linea BT.709 and Output source to sRGB:Appearance Punchy.

Ok, so when it comes to PP in Fusion (ACES way) steps go like this:
1. ACEScg > ACEScc (or ACEScct)
2 ...