We've got a mixture of things between here and GitLab at the moment. We'll slowly move more things over as time progresses.
Cura LE 4.13 development is still done on GitLab, however we're getting things prepped for our move up to Cura LE 5.X over here.
Marlin 2.1 is now fully on GitHub.
Most of our documentation and open source information regarding our 3D Printers is still over on GitLab.
Our GitLab