I managed to get a breadboard prototype of the major components (battery, MCU, BLE, watch, OLED) to a stable working state. I haven't bothered to hook up the accelerometer at this point, as that's somewhat of a bonus feature to me. The code is functional, but not great. I'll upload it once it's cleaned up a bit. But, I'm able to display text and symbols on the OLED which I send from my phone!

The OLED and BLE are situated in modules right now, but will be broken out into the components in the layout (in progress). The Arduino board is just there for the FTDI chip, and the whole system can run off the LiPol after programming. I'd like to start running some power consumption tests, but haven't figured out a good technique yet.

Image of the breadboard setup, with major sections highlighted: