Everything surrounding code: issues, CICD, etc, is obviously another story. But it's not a story that is answered by distributed git either. (though I would love a good issue tracking system that is done entirely inside git)
You might like git-bug:
This should be one of the very first links in the readme.
The tag-line covers it pretty well I thought?
"git-bug is a standalone, distributed, offline-first issue management tool that embeds issues, comments, and more as objects in a git repository (not files!), enabling you to push and pull them to one or more remotes."
That tells you what the feature is - if you need/want a more technical overview you can still get from the `README` to `entity data model` in two clicks (Documentation > Data model).