SkiftOS: A hobby OS built from scratch using C/C++ for ARM, x86, and RISC-V

That looks like alot of work, am surprised they built a custom build system, tho given the state of C++ build systems I can't really blame them.

Also why do OS devs seem to have a thing for making browsers? Shouldn't browsers be mostly agnostic to the OS?

The UI looks nice :)

Browsers are just application runtime ;)