freematics-firmware_v5-micropython/Doc/Building.md

Compiling the MicroPython sourcecode to .mpy turns it into "frozen bytecode" which results in lower memory consumption during execution.

git clone https://github.com/micropython/micropython.git
cd micropython/mpy-cross
make
cp build/mpy-cross <project root>

The upload.sh script will manage building this MicroPython project. If you get an error on the Erase step, that's fine and due to the files not existing to be erased.