Anyone capable of programming and willing to invest enough time will be able to learn Rust, in my opinion.
It might take some people months rather than days, but I think that is a desirable outcome.
Important low level software should be written by competent developers willing to invest the effort.
The effort should rather be invested into learning how underlying hardware works and introducing redundancy and observability into the system.
That's non-sequitur.
The problem here is that C is too basic, dated, with inadequate higher-level abstractions, which makes writing robust and secure software extra difficult and laborious. "Learning underlying hardware" doesn't solve that at all.
Debian supports dozens of architectures, so it needs to abstract away architecture-specific details.
Rust gives you as much control as C for optimizing software, but at the same time neither Rust nor C really expose actual underlying hardware (on purpose). They target an abstract machine with Undefined Behaviors that don't behave like the hardware. Their optimisers will stab you in the back if you assume you can just do what the hardware does. And even if you could write directly for every logic gate in your hardware, that still wouldn't help with the fragility and tedium of writing secure parsers and correct package validation logic.