My Shorty is up and running (mostly) - I made a mistake during component substitution for U1, selecting a 1.2v instead of 1.85v. That's on order, but has delayed the final fitting and calibration. Corrected BOMS are attached.
I also blew up the first STM32 Micro as a result of a dumb ground loop issue that caused 15vAC on the tip of my soldering iron. The STM32 drew 60mA instead of 3mA on power up! That took a while to track down the fault and root cause.
Also, my cheap Chinese ST-Link v2 clone had the plastic embossed triangle (indicating Pin 1) on the 2x5 PIN header in the wrong location with respect to the actual pin wiring. That also cost me a bit of time.
Once these issues were straitened out, programming was strait forward using STM32-Cube-Programmer. While putting in an order the 1.85v LDO above from Mouser, I decided to add some STM32 Dev Boards to get to free shipping. Reading more on this device, I think it will replace my aging ATMEGA platforms.