AMA: Microsoft Viva: Deployment and adoption

For managers, Insights provides aggregated collaboration information about the team. Only managers whose team meets or exceeds the Minimum team size setting can access manager insights. The size of the team counts the manager and all the employees who directly or indirectly report to that manager within the organization's reporting hierarchy. This minimum number can be adjusted by an admin, but the minimum required setting is 10 team members. https://docs.microsoft.com/en-us/viva/insights/use/manager-settings