I'd focus on high level APIs, managed code and JIT, and stuff like that, and everything would be written in Rust plus a scripting language for everything that i

I'd focus on high level APIs, managed code and JIT, and stuff like that, and everything would be written in Rust plus a scripting language for everything that isn't performance critical. More realistically, I just wouldn't build an OS either. That would be a nightmarishly large project!