Can you elaborate what you mean by go directly to the server? My thought is that commits can exist on a server, but not on nostr just as they do on a local repo today before someone pushes to GitHub. As long as the key commit (for a PR or a release) is pushed to nostr and can be found on a tagged server then all all the history can be retrieved from any server that has a copy of the commit.

Generally, my thought is that the git servers will maintain the full history since git already does that well. Nostr is just there for relay discovery and an anchor for discussions