GitLab
Homepage: https://docs.gitlab.com/omnibus/docker/
If Gitea isn't powerful enough for you then consider GitLab. It's a much more powerful (and consequently bigger) Git repository solution that includes a suite of code analytics. On the other hand it requires more RAM.
Usage
Set gitlab_enabled: true in your inventories/<your_inventory>/group_vars/nas.yml file.
To make GitLab available externally via Traefik set gitlab_available_externally: true in your inventories/<your_inventory>/group_vars/nas.yml file.
Set gitlab_root_password to initial root password. The after container creation and start-up login with user root and gitlab_root_password password. From there you can proceed to create additional users and further configure the application.