download & install docker desktop for mac
cd SynestiaOS/Docker/
docker-compose up -d dev-prebuilt
docker-compose exec dev-prebuilt bash
root:~/SynestiaOS
$> cd Scripts && ./compile_and_run.raspi4.linux.sh
cp Scripts/buildRaspi4/bin/kernel.img <your-sdcard-root-folder>/Kernel7l.img