Thanks for explaining your motivations @orbifx, and for kickstarting this discussion. In the longer term, I definitely want to reduce the coupling on GitHub, but of course it’s just difficult to know where the short-term projects to start this off are.
There are a couple of efforts underway already to make this possible. The OCaml CI is based on Datakit, which has an API bridge to GitHub that mirrors PRs into a local filesystem controlled by Irmin (a Git library in OCaml). This in turn has a bidirectional bridge which writes back to GitHub, but could also serve the results directly (as https://ci.ocamllabs.io does for opam-repository submissions).
We’re also working hard on a usable email implementation that works on real-world contents. One idea for an immediate next step would be to construct an email->Irmin bridge that would receive git patchbombs and convert them into GitHub PRs via a bot account. That should satisfy your (reasonable) request to not have to have a GitHub account to contribute to opam, and also let us maintain the existing workflow. Is this something you’d be willing to contribute to?
Note that, without a longer term plan, I am resistant to just kicking off an official ocaml.org GitLab instance. It’s a lot of work to maintain, and simply splits our already stretched infrastructure maintenance efforts. However, I am very open to such a longer term plan being written to motivate the move. I already operate https://gitlab.com/ocaml-platform for some CI runner tasks, and am in the process of requesting access to gitlab.com/ocaml for more official use.