I think you would have to compare against total users currently in VR games to get a percentage popularity. For example I own a Oculus and am not currently playing VRChat on Steam, however that doesn't mean I've never played VRChat off of the oculus store.
Steam charts is only tracking players in Steam with the software launched, VRChat is also available through Oculus's own stores for desktop and quest, where it has 8,000 reviews for the quest version and is fourth overall in popularity after Beat Saber, Rec Room and Youtube VR.
Rec Room (which looks more like what Meta has in mind, they even did laser tag) is at 13,000 or so reviews, but is only at a 30 day peak of 3,600 users on Steam.
[1]https://www.oculus.com/experiences/quest/section/55416991837...