MicroPython [0] for instance gets mainly used on microcontrollers. Hard to tell how common it is, but it definitely gained some traction, also runs on the micro:bit [1] which gets used for teaching. Which isn't surprising: Python is easier for beginners than C. i don't know about other implementations though.

[0] https://github.com/micropython/micropython/ [1] https://www.microbit.org/