You seem to forget about Issues, Milestones, Projects, Wiki docs and more.
Probably a naive question, but is there some way for all these elements to held in a git repo as well? Just move all your issues/trackers to another platform?
There are some approaches, e.g. https://github.com/dspinellis/git-issue
But I don't think there's much standardization around this type of git usage, and I'm not sure how efficient it would be for large repos.