volume control

Hi what would be the best way to control a receiver volume through homekit? I thought maybe volume could be remapped as a dimmer somehow? -40 - 0 mapped to 0-100 maybe?
Or even a simple volume up +5/-5 would I have to make a switch for each of these and use the same vol up for on and off? Seems a bit clunky and I'm not sure how the voice command would work. "hey siri turn on volume up" isn't ideal.

Thanks for any suggestions

Sorry for the late reply, I've been on a project. It depends on how your receiver talks to Indigo. Is it plugin based? IR controls?

My reciever is controlled with the Yamaha rx plugin for indigo. It has options for vol up vol down and set volume and it returns the volume status.
A work around I have found for now is an equivalent homebridge plugin which does exactly what I'm looking for. Volume shows up as a dimmer light.
Cheers