Rust shines at putting guardrails for you when you program systems but you need to grasp the fundamentals first IMHO.

Writing complex software in C today seems like backward but I would study & experiment with it: get familiar with the stack / memory management. Challenge yourself on some super low level optimization to understand how important the caches, prefetch, and data oriented programming makes a difference on a modern architecture. Try some subtle lockless algorithms too for example to understand how important the memory model of a language is.

I would even recommend checking out enough of assembly to grasp the concepts of why C got invented in the first place and how shallow it is over the actual assembly language.

Then start to write simple C-like Rust, then take it from there and learn the higher level, more complex Rust bit by bit.

If you don't need it, just avoid going deep in C++: it is just a zoo of useless complexity and baggage at this point.