It likely refers to the popular STM32F4 Discovery board [0], which is a devkit for that family of uCs. Good for prototyping, has an onboard programmer and everything. It has 1MB of flash, so I think this line means "if you wanted to use this board, you'd be better off with a full RTOS that can make use of that code space, rather than M2OS which is optimized for single-kB flash sizes".

The rest of your comment I agree with. It seems to be a half-baked academic project. Might be interesting if you know anything about Ada, which I don't.

[0] https://www.st.com/en/evaluation-tools/stm32f4discovery.html