What is sitting inside LED array so that I can create my own drivers?
If you open the device up you will find a bunch of chips and will be no wiser as the device is software controlled.

Since it is already working over WiFi you should try and hack the protocol by eavesdropping on working messages. Something like Wireshark would be a suitable tool but it will take you a day or two to get familiar with it. You would then start to send very simple patterns such as one pixel, top-left, etc., to try to figure out the protocol. At the very least you should be able to duplicate a captured message sent from the app and try transmitting it from the Pi and see if it works. If it does then proceed with reverse engineering.