I was reading the AOV documentation and it just seems to state only lighting contributions can be output as AOVs. It would be great if a “fuel” AOV could be output in order to easily extract that from the smoke while compositing.
You may have figured it out already, but if not and if I understand you correctly, you’re looking to create an AOV for the fire itself with no smoke. If so, you can create an AOV for the emission. That should give you just the fire with no lighting contribution. Additionally you can create a. secondary emission which will give you the scatter, assuming you’ve enabled multiscatter.