It is common for a team to work on multiple projects, but would like to be able to see a global view of all issues of all projects and to do planning based on all issues. Therefore, you'll need to be able to see all projects in a group in the group view. To this end, I suggest making it possible to see all issues of all projects in a group centrally. For example, Redmine supports hierarchy of groups/projects.

This is a feature missing from many git hosting providers.