Samsung, Sony, LG and others are producing commercial microLED panels, mostly for ultra-premium, signage and commercial applications. The ultra-large size displays are made from small microLED modules, seamlessly tiled together.
MicroLED technology makes it possible to connect two tiles in a way that retains exactly the same pixel pitch even at the tile connection (this is something that is challenging to do with OLED or LCD displays). When the displays are active, it is indeed very difficult to spot the seam. When the display is completely black however, this is not the case.