IMO nix should not get in places where package management is done correctly (rustup/cargo), but definitely should when it's not done correctly (OCaml, C, python, etc.)
We use nix for our rust projects, for the following:
- consistent dev environment with all local dependencies (postgres, rustc, awk, etc.)
- building rust packages themselves
- building tiny docker images that run rust binaries
The official Rust tooling for nix still uses Cargo under the hood, and this makes it way easier to use and more consistently functional than the equivalent tooling for Python, JS, and similar, at least in my experience
