DSOS
64-Bit Bare Metal OS that I'm developing for the Raspberry PI 3B+. Some stuff is working for 4 as well, but not testing it yet.
Note: Inspiration for this came from this repo, which is a great tutorial on learning OS development, looks like it's gone stagnant the last couple years though: https://github.com/s-matyukevich/raspberry-pi-os .