Not being a Volumio user here, I think it’s probably better to check their fora.
While working on my Roon-dynamic-range-metering-bridge I think I’ve seen links to threads regarding setting up and using the peppy meter plugin…
Edit:
Do you have peppy meter work as Volumio plug in yet?
If so, then just grouping with whatever zone you want it to display should do the trick, no?