I was wondering why this would need the power of a Pi for a basic control application. It seems it’s just used as a user interface for programming the MCU that actually controls the system.

While STM32 handles hardware-level tasks, the Raspberry Pi Zero 2W manages high-level control and user interaction. The RootMaster can be programmed with Python, C, C++, or other programming languages and is useful for applications like Hydroponics automation, water circulation, and environmental control.

It would be a lot cheaper without the Pi and just an interface to hook it up to something like HomeAssistant so you could program multiple of these from a central location.