I choose to use Circuit Python for programming the custom part of my payload, for convenience:  the vendor of my nontraditional components offers free code libraries and technical support for the layperson. 

I am placing links to the code tutorial pages for each relevant component here, for my own convenience:

First, the microprocessor board needs firmware to be uploaded via USB to its flash memory.  To enable this feature, I must connect the B0 pin on the board to the 3.3V pin,

and then press the Reset button on the board, while it is connected to my PC’s USB.   I will find the microcontroller board listed in the Device Manager in the Windows  operating system of my PC, under USB / Serial Devices.  The detailed instructions for uploading the firmware are linked here. 

After firmware upload, the microcontroller board will show up on my PC as a new drive called “CIRCUITPY.”

I will find the /CIRCUITPY/lib directory in the microcontroller board, and upload the code libraries that  I will need.  If the microcontroller board has plenty of flash space, then I will simply upload all of my vendor’s CircuitPython libraries.  After that I will  be able to upload my  python program.