I would really like to see more work on improving the use of Nim for programming microcontrollers. I stumbled on to https://github.com/elcritch/nesper recently and it looks neat, but I had issues getting my code to compile. Improved support for other MCUs like the esp8266 and atmega32u4 would be really cool and useful. It would be nice to have Nim as a higher level alternative to micropython or lua in the embedded world (your only other real alternatives being C/C++ or Rust).
I also found this https://disconnected.systems/blog/nim-on-adruino