I am looking for a suitable recommendation of an MCU development board that I can use to run a flight controller program in real-time that has a refresh rate of 250Hz or more.
Hi @Lucky , take a look at the Audupilot project:
https://ardupilot.org/copter/index.html
https://ardupilot.org/rover/docs/common-autopilots.html#common-autopilots
Regards,