I agree with you about Rust and the web - it's a great fit for a performance-oriented web backend.
Personally, I actually think it's a worse fit for things like kernel/embedded development than for web backends. The ergonomics of Rust are so Javascript-y that the web is natural, and other environments where C is used are a lot messier and trickier.
I wish ReasonML took off more. It's an OCaml dialect which reminds me of Rust with a garbage collector, which is unsurprising given the Rust compiler's history being initially written in OCaml and where a lot of its ideas stem from, such as exhaustive pattern matching, the Result type, functional programming being as performant as imperative programming ("zero cost abstractions") and so on. ReasonML was developed at Facebook by the creator of React and it was supposed to be used as an alternative language than JS for writing React.
However, it didn't have much support after TypeScript took the JS world by storm. If it had, we might have seen the same great Rust-like benefits on the frontend as well, and perhaps the backend too instead of NodeJS.
The productiveness, safety, and beauty (seriously!) of the surprisingly numerous Rust kernel and embedded projects suggests otherwise. That use case took off very quickly in Rust world.
Personally, I actually think it's a worse fit for things like kernel/embedded development than for web backends. The ergonomics of Rust are so Javascript-y that the web is natural, and other environments where C is used are a lot messier and trickier.