From the name I thought this was about learning NixOS, and they found a very clever name

Maybe the author could add a small note that this is not about that, and refer to something official about NixOS?

Anyway, I like the idea of the project!

This dedicates at least as much time to discussing the eccentricities of the underlying Rust implementation (and the Rust language itself) as it does to discussing the underlying low-level hardware/software concepts. Since this is very much still a work-in-progress (only the first three sections have been fully fleshed-out), I have a suggestion to make: please make it more language-agnostic, with a greater focus on the fundamentals versus the implementation.

Looking forward to going through the lessons

This is an ambitious project. Might I respectfully suggest that you use your favourite AI (or an English-speaking friend) to fix your many grammatical errors and typos? For example "Note: ALL the syntax highlighting of the Rust code is custom and create by me! If you see and bug, please write in the comments or submit an issue." should be "Note: ALL the syntax highlighting of the Rust code is custom and was created by me! If you see a bug, please leave a comment or submit an issue." Also, Rust, not rust. Any many more.