This was attempted multiple times in the past. None succeeded, in large parts because at a fundamental level issues are a synchronisation point, making issues part of the repository adds overhead and complexity but doesn't really give you anything, and furthermore it increases complexity for reporters.
All the issues, wiki, PR review are stored in Git as well. You still need a Pagure instance (that you can self host if you want) to provide the web ui, but you can easily just clone the repo and put it to a different instance, keeping all your metadata.
I know of an attempt to implement an approach to track issues and code in a decentralized manner with SIT[0]. Unfortunatlely the project seems to be dead.