PyTorch and the PyPI supply chain

Exactly. There is tooling to help find vulnerabilities, but yes, the basic premise is that you the developer must explicitly give permission for some dependency (even transitively) to be updated. Doing anything less gated than this is really just giving other developers permission to execute arbitrary code on your machine.

Both of these are relevant:
https://go.dev/blog/vuln
https://go.dev/blog/supply-chain