I was fascinated with operating systems for a long time. And the thought of learning more about them always sits at the back of my mind. But I can identify at least a couple of reasons why I never did something in that domain. While I can read C-like languages, and with some effort, understand the code, every time I looked at Linux kernel source code, I saw unicorns and fairies. I would say that the kernel is not beginner-friendly, which is not a bad thing. But I felt like I needed to invest a lot of time before contributing. And some things were more fun and sometimes profitable than properly learning C and understanding kernel. So I never did.
Despite all of that, I occasionally read articles or news on that topic. And when I saw “Just for fun”™ Linux on Rust rewrite, I immediately jumped in. Maybe “jumped in” sounds over-enthusiastic because I know nothing about the kernel development and still don't feel comfortable with Rust. But anyway, I can read and navigate the source code, identify spots that I can fix, and fix them. Which is a vast improvement over the original kernel for me :)
If you can relate to what I wrote above, check out Kerla. It is in the early stages of development, so people with all levels of knowledge can find what to do. There are a lot of decisions to make, a lot of code to write.
And yes, it is fun