Yes, it is possible, it just involves a lot more programming. You could even build a tiny button or LED matrix. With the 8 pins of J5 you could have a 4x4 Matrix for instance, or a 3x3 matrix and 2 LEDs or a 3x2 matrix and 3 LEDs [...] You can do what you want with most of the input/output pins, it's just a matter of programming.