This specific finding is minor, but its implications are not IMHO. From the article it appears the researchers consider this a discovery in effect.

If consumer hardware is already capable (in many settings) of reproducing what were formerly research-level and industry-grade techniques, it may be a transformation in more areas of technology than would be obvious. I am very curious to see if there will be further findings in this area.

Smartphone grade lidar == FaceID ?

So this only works if you have walls opposite of this corner?

Why not just place a mirror at 45 degrees in the corner? That way you don't need the lidar but you can just look around the corner? It would also work better with the lidar.