Wahoo made a unit a few years ago called the Wahoo RFLKT and RFLKT+. It did exactly what you are asking and displayed the data from certain phone apps. It did not show any maps, just data. I used one for several years and loved it. Unfortunately, Wahoo discontinued them when they introduced the Elemnt bike computer. Amazon is showing one left for $54.99 but it's used. At the moment, the only cycling apps that I know of that still supports the RFLKT is Cyclemeter and the Wahoo Fitness app. Both apps allow you to customize the RFLKT's screen layout to your liking but Cyclemeter gives better customization. Cyclemeter is $10,00/year, Wahoo Fitness is FREE.