The real game changer would be completed Federation[1] support. This is why I am donating both Forgejo[2] and Codeberg[3] and urge everyone doing the same, to give more time and resources for the Forgejo team to implement it properly.
Another good contender is the Radicle[4][5] which is completely decentralized on top of the Git.
federations are the only decentralization model that scales, the issue is that most "federated" systems are actually just "distributed centralization" eg mastodon.