This is fairly easy to wire up on Linux using v4l2loopback and pyfakewebcam.

I am currently using a little setup that uses OpenCV to acquire frames from the real camera, TensorFlow/BodyPix to compute an alpha mask for the foreground (me) and then OpenCV again to transform and composite myself behind news desks and into car infotainment screens and the like, eventually writing it to a virtual webcam I can use from Zoom (over its own virt bg feature this adds the layering and perspective transforms), Jitsi, Teams, etc.

The above looks like another fun thing to add. Time to go full Who Framed Roger Rabbit? ...