"dead front" LEDs, sorta...

Yes, you would be able to achieve that. I’ve used it on a curved surface (Sorry nothing I can post, yet) for an identical effect.

The film is the first surface, which protects the ink below and provides the smooth glossy surface. You can achieve other surfaces by using textured films.

The ink is below that and you can print your graphics with different opacity. That canon printer is likely the same process, just with a solid black layer on top and then the artwork below it. Smooth black surface to the user until the light shines through.