I agree that would be nice, but NPM absolutely will not do any basic supply chain integrity work. They are actively opposed to it citing concerns that it might turn off lower skill developers that would be too annoyed by tapping a yubikey to sign releases or code. I have talked to them enough times over the years to have completely given up here.

Whats even more stupid is they actually started mandating 2FA for high risk packages, and FIDO2 supports being used to actually sign artifacts, but they instead simply use it for auth, and let releases stay unsigned. Even the developers they insisted hold cryptographic signing keys, they insist on only throw-away signatures for auth, but not using them for artifact signing to prevent impersonation. It is golf clap level stupid.

Consider them a CDN that wants to analyze your code for AI training for their employer and nothing more. Any security controls that might restrict the flow of publishing even a little bit will be rejected.