Writing an operating system kernel from scratch

For those who want a "packaged" experience doing this same kind of work, there's "Operating System in 1000 Lines of Code" (https://operating-system-in-1000-lines.vercel.app/en/), I followed it a while ago in Zig (which meant translating C code snippets to Zig) and had a good time. I have the code and VODs here: https://github.com/kristoff-it/kristos/

What would be the level of Zig knowledge needed to do this exercise?

Or, asked differently, with no knowledge of Zig, what would be a realistic approach to trying this out? (Assuming an interest in learning Zig, with a background in C++)

I could easily understand stdlib code of zig after building some stuff for 2 days. Would be different for everyone but it is fairly easy