Right now there are indeed zero people working on the reproducibility of crates and other language-package-manager packages, but there is no reason why the site

Right now there are indeed zero people working on the reproducibility of crates and other language-package-manager packages, but there is no reason why the site would be restricted to distro packages once the language-package-manager communities start working on the reproducibility of their packages. Some distros actually do run `cargo install` or similar during build, although Debian does not indeed.