It's also "pointer" based, but like vendoring, it's up to you whether or not you want to keep files in the repository. It also seems to be intentionally built for the use case where you modify something from upstream, because if you do have local changes, it detects them and won't overwrite them without your permission.

There's a whole umbrella of similar-ish utilities. The one that I think does almost the same thing is: https://github.com/mullvad/git-carbon