Hi!
Mmmm... I've never asked myself that question :) I have a Varjo Aero around too and a G2, but I'm pretty sure it's impossible to mix those two units. The HP reverb controllers are made for WMR inside-out tracking but the Varjo uses the steamVR lighthouses.
Try what this guy has done. According to the videos, it seems to work. https://store.steampowered.com/app/1366950/Driver4VR/