If anything, what are you doing about supply chain for the existing code base? How is cargo worse here when cargo-vet exists and is actively maintained by Google, Mozilla, and others?
That said, `cargo-vet` is easily the best tool for mitigating this that I am aware of and it exists for Rust and is actively maintained by Google, Mozilla, and many others. I think it's fine to say "Rust encourages using more dependencies" but it has to be acknowledged that Rust also brings with it the best in class tool for supply chain security.
Could it be better? Absolutely. God yes. Why is cargo giving access to `~/.ssh/` for every `build.sh`? Why do package managers not make any effort to sandbox? But that's life today.