I have never seen a picture of the cartridge, but based on what I have seen from playing around with the ROM, the Fire Bird works very similar to a GB Sacker or the Magic Editor Card by Yobo. It has cheats for official games (I do not know if it has any for unlicensed ones) and uses what are called Golden Finger cheat codes. Also, if you emulate it, it will act as though it was plugged into itself
Edit: Just scrolled through the list of games it mentioned having cheats for. Shawu Story was on it, so it has cheats for at least one unlicensed game