The extension provides access to the new Pull Requests explorer in VS Code, available in the Source Control view. The marketplace entry says the new tool was published Sept. 7, and as of this writing ...

On the VS Code Marketplace, the GitHub Pull Requests extension shows 51,697 installs (though 233,079 downloads) and an average 4.7 rating (5 star scale) from 15 developers who reviewed it. Source code ...

Developers commit their code as usual to GitHub or another repository, and then add Amazon CodeGuru Reviewer as one of the code reviewers. It opens a pull request to vet the code.