The following script installs esp-idf, the required dependencies and then builds MicroPython for the ESP32.
apt -y update && apt -y install python3 python3-pip cmake # Install esp-idf git clone --depth 1 -b v4.4.3 https://github.com/espressif/esp-idf.git /opt/esp-idf cd /opt/esp-idf && git submodule update --init --recursive && ./install.sh # Clone micropython git clone --depth 1 -b v1.19.1 https://github.com/micropython/micropython.git /opt/micropython # Build micropython cd /opt/micropython/ && make -C mpy-cross # Build micropython@esp32 cd /opt/micropython/ports/esp32 && source /opt/esp-idf/export.sh && make submodules && make -j4