>What I find really sad is, that they have like a million bindings to every programming language there is (including one that they made up) and I have no idea how they want to maintain that codebase.

I believe that's to do with gobject introspection (see *). From what I understand they mostly generate bindings through gir files. It's actually really cool what they've pulled off with it.

* https://viruta.org/the-magic-of-gobject-introspection.html