Mosaic Lights is a Budapest startup that launched an LED panel that can be installed directly behind transparent or translucent tile.
You can see a brief glimpse of the actual product in their installation video. Looks like the LED panel has direct interconnects to other panels. But I see that they are using mortar or some other quick-set to adhere the panels directly to the wall. This seems highly problematic: If anything fails, you have to rip apart the entire tile wall? You can’t just rip open a part of tile wall — the mortar repair color will never match.
I think this would be a far more viable concept if the actual tile could somehow be panelized for access to the light engine.