Good news! We found a different way to go about this! A way with single color LEDs, much smaller buttons, and a total of 4 WIRES coming out. WOW. It’s called the Adafruit Trellis. I soldered on the LEDs and, after some trial and error, got it to light up!
Oh yeah, there’s also this: Adafruit just within the last week came out with a support for tiling up to 8 of these Trellis boards together, and they have example code and libraries to help get it going. AKA EXACTLY WHAT I NEEDED . It’s time to start making music.