Cool! That is really interesting. ActivityPub would be great for this. I've added in links to the issues below:

Gitea:

- https://github.com/go-gitea/gitea/issues/1612

- https://github.com/go-gitea/gitea/issues/184

Gogs:

- https://github.com/gogs/gogs/issues/4437

Gitlab:

- https://gitlab.com/gitlab-org/gitlab-ce/issues/44486

- https://gitlab.com/gitlab-org/gitlab-ee/issues/4517

edit: added gitlab enterprise link (plus formatting)