They are using tradicional RPM for packaging.

The cargo.toml workspaces relates more to make IMHO.

Correct, that toml file allows you to build everything from that level, and open editors on that folder with the language server functioning. RLS requires a cargo.toml file in the root of the workspace even if it just points at other directories

Wouldn’t something like Bazel make more sense? Using cargo to track inter-dependencies seems a bit weird to be honest.

well it's interesting since they only need to learn the rust toolchain, not something else.