I've used git-bug[1] for issues and it works pretty well. The web-ui is lagging behind and PR support would be everything you'd need to ditch a central-hosted web instance.

[1] https://github.com/git-bug/git-bug

FWIW, I have a new and much better webui that I need to release. I'm also planning to work on PRs and other stuff around the end of the year.