Feature Request - 3D overlay apps

I know that XR_EXTX_overlay is a provisional extension. It looks like it’s the successor to OpenVR’s VROverlay functionality.

I am very interested in injecting 3D objects in another app’s scene as an overlay app, rather than 2d textures. Is there a plan or existing request for this feature? If not, I’d love to hear whether I’m the only one dreaming about this.