Moving XR Origin to calibrate multiplayer shared spaces

Looking for a cheap hack to calibrate worlds for a shared space multiplayer, multiplatform experience: Since the protocols differ for multiple headsets, I was thinking of just placing a gizmo at a cross point IRL, and that will move the entire world (an alternative would be looking at an image target and aligning on its location). What would be more elegant would be moving the XR Origin, but I haven’t found anything definitive. Is this a valid path? Anyone can give pointers?