AFAIK Linux is using rustc directly, without cargo.

And just an anecdote, Asahi Linux devs said that Rust made it very easy (maybe relative to working with C) to write the drivers for the Apple M1 and M2 series, so it seems that the language has his merits, even without the cargo ecosystem.

Also Rust will only minimize certain kinds of bugs, others are impossible, a few years ago (I believe was Microsoft) that said that 70% of the bugs found were memory related [0], it means that Rust would have prevented most of those.

Maybe Rust is not the best answer, but as for now it the most proven answer for this particular problem, who know of Zig or other language will replace both C and Rust in the future.

[0] https://www.zdnet.com/article/i-ditched-linux-for-windows-11...