> The biggest orgs tend to run all of their builds sandboxed, including what happens with build.rs. It's part of how they enforce dependency management day to day, but also helps protect against supply chain attacks.

Sandboxing doesn't completely prevent supply-chain attacks. You can avoid getting persistent malware on your CI machines, sure. Exfiltration of tokens and secrets during build? Maybe in a small handful of CI setups where admins have carefully split the source fetch, or limited CI network access to Nexus. Exfiltration of tokens and secrets and/or backdooring after the software has been deployed to production? No, build-time sandboxing doesn't help here at all.

On all developer machines as well? No. Very few big orgs do this and only for mission-critical stuff. Some very important ones have docker-based sandboxed workflows or SSH-to-sandboxed-cluster workflows, or air-gapped laptops but that's very, very rare (I worked in air-gapped environment for a bit and it was a massive pain).