OK I read up a bit on the ZMK flashing process. I got my github repo set up and the action ran OK and built me a firmware. I can see the blue and orange (charging) lights on my MCU when I plug it in over USB and flip the power switch on. I cannot however see it in my iphone's bluetooth pairing screen, and the linux UI for this is just a see of undifferentiated hardware addresses so I have no idea if the MCU is in there somewhere amongst a dozen other speakers, headphones, etc. While waiting I installed the remaining switches on the left hand as well as keycaps. Will probably need to get some help on discord in order to move forward. The next goal would be to flash the default rae_dux firmware, pair it to my laptop, and get a keypress to work.