You can add integrations to Works with GitHub that integrate with GitHub but don't meet the GitHub Marketplace requirements.
From Works with GitHub, users can explore integrations that help them expand the functionality of GitHub.
Users can't purchase integrations on Works with GitHub through GitHub. Instead, users will be redirected to the integration's site to learn more information, purchase, and install the integration.
For information on requirements for Works with GitHub integrations, see "Requirements for adding an integration to Works with GitHub."