I propose to try GitHub organizations for communication,
coordination, project management, etc.
We can create an organization like this: https://github.com/debian-gsoc
and use the tools available for managing teams, projects, etc.
By the way, the organization https://github.com/debian
taken for another purpose.
So, why not use https://salsa.debian.org/
GitLab is an imitation of GitHub, but not as good as it. GitLab has lacking features. In particular, GitHub has features for organization management, including team management and project boards (kanban):
I did not see on salsa anything like these at all, maybe I have missed them. These features are exactly why I am proposing to use GitHub, and salsa does not have them at all.
So, why not give GitHub a try?