@masklayer I think so? You might need to convince Steam VR that one of the controllers is the head, which is at least possible with Vive Trackers.
Hm. One sec.
@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.