An unmanned coffee shop in Singapore, called Crown Coffee, installed LG Electronics transparent OLED signage. Customers at the shop can view promotional videos or details on their orders, while a robot makes the coffee which can be viewed through the display:
These are LG's 55-inch Full HD panels, that feature a transparency of 38%.
In February 2019 LG Display started producing its transparent commercial OLED displays, and later the company announced doubled its transparent OLED production capacity. Here is another interesting installation by LG in Shenzhen's metro.