At the Free Software Foundation Europe (FSFE), we use a git.fsfe.org (based on Gitea) to host all our code and websites. This includes a full archive of the commits to fsfe.org which definitely has some historical value ;)
How could this be achieved? I learnt that there is no connector from Gitea to Software Heritage, but perhaps there is some automatic scanner for the public repos we host.
Unfortunately we do not have the resources (mostly regarding Go skills) to come up with a patch for Gitea's code, but I would be happy to assist, test, and give feedback!
PS: @zack asked me to file a feature request for my inquiry here. If I did not sort/label my request correctly, please feel free to edit.