tl;dr version:
While writing a little terraform module to manage github repositories, team permissions and branch protection rules, I ran into an issue where github_team_repository resources need the team ID, but github_branch_protection resources need the team slug.
This was annoying as I wanted the module to have a single variable which served both purposes. I ended up having a variable var.teams_pull which accepted a list of team slugs. Using the github_team data source I was able to derive each team’s ID.
See the team_id parameter on the github_team_repository.pull resource below to see how to access it.