Now that we've got the formalities out of the way, I've been having a nightmare of a time matching Karma renders in the viewport / mplay. The ACES transform from ACEScg just never looked right, colours ended up too saturated.

But I've cracked it for davinci resolve. Use EXR output:

Houdini Settings:
Edit > OCIO Settings > ACEScg
(Setting this to acescct fucks up the viewport)

Karma Render Settings
Image Output > AOVs > Component Level Output > Output Colorspace > ACEScct

Resolve Project Settings:
Pic-related + in the colour page, project nodes add an aces transform with the following settings:
- Input Transform: ACEScct - CSC
- Output Transform: sRGB
This will let you mess withe gamut compression and do post-srgb changes

This will exactly match what you see in houdini.