- [NetBsd](https://www.netbsd.org/). Still very active
- [uCLinux](https://sourceforge.net/projects/uclinux/). Need to take a closer look.
- [Gloworm](https://github.com/transistorfet/gloworm). This might be a good place to start as it's fairly basic and it doesn't look like too much effort would be required.
+
- Linux - here are a few links to folks who have done something similar: