- https://github.com/GovTechSG/terraform-iam-users-gcc
- https://github.com/GovTechSG/terraform-iam-group-gcc
- https://github.com/GovTechSG/terraform-iam-group-role-gcc
These are the modules related to the sharing. If you're just looking for the modules required to refactor your team's users, you can start from here.
Something that was alluded in the sharing is that policies should always be applied to group instead of users itself. Users itself shouldn't have any policy applied, so all the pre-made policies are on the group level; this includes the permission to assume your base role, as well as forcing MFA, and allowing your users to rotate their own access keys.
The order of creation should be.