I think the firmware is finished!

The QMK docs were difficult for me to understand, and I ended up following parts of a bunch of other tutorials. Compiling the firmware took longer and longer every time I added something else. Eventually, it took 55 minutes to compile.
Instead of trying to figure out how to use the OLED display, I added seven LEDs in a 7-segment display orientation and used that to display the layer number! I also designed some decorations in Inkscape to put on the top plate of the case.