It's possible, and common, for NPM packages to download additional binaries at install and/or run time. These would not be included in the hashes, and are essentially untrusted, often hosted on random S3 buckets. I'd hope there are checks in the official project to ensure these aren't being used, but there aren't any checks in this project.
My employer uses artifactory as a mirror of npm and one step of adding a package to the mirror is installing it on a VM/container with no network access. If the package has a "postinstall" script requiring internet access then it will fail. There's also code scanning that will find at least casual attacks like "download and run this crypto ransomware".
Also, it depends how determined your attacker is. If they write code to detect whether they're being installed in the vscode project, have access to commercially available security scanning tools to ensure they evade detection, etc...
