@masklayer Answer: yes, but you have to use the SteamVR version and the experience wasn't too great since you have no point of reference for your camera rotation.
Might be better if you have a puck to track your head position and rotation, or do some other magic in OVR.
@masklayer Which, to be clear: you'll still need to have _something_ mapped as the head position for VRChat to work at all with motion controls (https://www.reddit.com/r/VRchat/comments/ag33wm/help_desktop_mode_with_motion_controls/). My test was turning the headset off and using both controllers; it still mapped the head position to my Index.
If you map something to "head" in SteamVR, that should still work, and a Vive Tracker (or equivalent) can serve this purpose. But even assuming all that, the experience wasn't great.