Another interesting topic to look into is forge federation. Forgejo [0], the code forge on which Codeberg is based is one forge software that intends to federate their repositories between server instances over the network using ActivityPub protocol extensions such as ForgeFed [1] and F3 [2] specifications.

[0] https://forgejo.org

[1] https://forgefed.org

[2] https://lab.forgefriends.org/friendlyforgeformat

I've previously used gitolite for such kind of set up https://gitolite.com/gitolite/index.html The configuration is done by pushing on a specific gitolite-admin repository