3D display technology creates an impression of depth on a flat panel, and in signage it almost always means the glasses-free kind. Two families dominate: autostereoscopic panels that send slightly different images to each eye through a lens layer, and forced-perspective content on a curved or corner-mounted screen, the "anamorphic" billboards that appear to contain a moving object.
The second is the one delivering nearly all the results people have seen. It needs no special panel at all, only a screen with a physical corner or curve and content rendered for one viewing position. That is why the striking examples are landmark installations rather than products you can buy per unit.
The caveat is the viewing cone. Autostereoscopic panels work in a narrow set of positions and degrade to a doubled, blurry image outside it: fine for a kiosk where one person stands in a known spot, poor for a corridor people cross at any angle. Forced-perspective content has the same constraint in a different form: it only reads correctly from roughly where the render assumed the viewer stands.
Budget accordingly. The content is bespoke to the installation and cannot be reused across a fleet, which puts this firmly in the flagship-site category rather than the network rollout.