Snek is a tiny embeddable language targeting processors with only a few kB of flash and ram. Think of something that would have been running BASIC years ago and you'll have the idea. These processors are too small to run MicroPython.
Snek borrows semantics and syntax from python, but only provides a tiny subset of that large language. The goal is to have Snek programs able to run in a full Python (version 3) implementation so that any knowledge gained in learning Snek will transfer directly to learning Python.
Github and list of supported microcontrollers: https://github.com/keith-packard/snek