An ActivityPub federated service over-top Git might be an interesting avenue to investigate, allowing for a code review/issues/release/etc... system that could be VCS-agnostic.

I hear this a lot, and I still don't really get it - git is already decentralized! And not just federated, but truly decentralized where everyone has their own copy of the data. An issue tracker built on top of the git protocol, where issues/PRs/whatever arbitrary other rich text content you want lives inside the .git directory alongside the source code would be much more in the spirit of git. And you could build a pretty modern web interface on top of that!

Please help make this happen. A decentralized SCM platform built on IPFS or fully integrated into Git is my dream of the future.

Thats not needed. Just bundle the data in the same way that branches and other data is so I can do a git fetch and it pulls in everyones comments.

I want to add code reviews in git-bug at some point: https://github.com/MichaelMure/git-bug