Instead of or in addition to a United Nations Assembly of nations, there could be an assembly directly elected by people.
Each person could self-identify with a group, and that group could be proportionately represented in an assembly.
This would give representation to people who are ethnic minorities, and thus largely left out of the selection process by many nation states. For example, the Kurds could have representation.
The Assembly of Peoples could have authority to appoint governing bodies, such as a Council of Elders. It might also make decisions such as approval of rules and guidelines for action by international military or international satyagraha teams.