Zephyr www.zephyr-soft.net Zephyr is a small real-time operating system RTOS

 https://en.wikipedia.org/wiki/Zephyr_%28operating_system%29

https://github.com/d-mozulyov/Tiny.Library 

https://se.ewi.tudelft.nl/desosa2019/chapters/zephyr/

https://slowbootkernelhacks.blogspot.com/2020/11/zephyr-rtos-project.html

 Python 3: Script interpreter and packages
 CMake/Ninja/Make: Build system
 Device Tree Compiler: Compiles device tree hardware descriptions
 Toolchain: gcc for Arm, RISC-V, x86, etc.
 Debug/Flash Tools: J-Link, pyOCD, OpenOCD, etc.
 West: Custom tool for repository management, build/flash/debug assistance, and image signing
 Zephyr Git repositories: The source code!