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. Make sure you aren't connected to the device's serial port when running the script.