Since Rust is not directly hardware, here is a nice tutorial on some simple OS basics: https://operating-system-in-1000-lines.vercel.app/en/

There was also some Rust specific OS tutorial somewhere that was written nicely, but I can't find it right now.

Also if you want to get real hardware, there is the neorv32 that has nice documentation: https://stnolting.github.io/neorv32/ https://github.com/stnolting/neorv32

It's a risc-v core written in VHDL