You may want to look at AzGovViz https://github.com/JulianHayward/Azure-MG-Sub-Governance-Reporting
AzGovViz is a PowerShell based script that iterates your Azure Tenant´s Management Group hierarchy down to Subscription level. It captures most relevant Azure governance capabilities such as Azure Policy, RBAC and Blueprints and a lot more. From the collected data AzGovViz provides visibility on your HierarchyMap, creates a TenantSummary, creates DefinitionInsights and builds granular ScopeInsights on Management Groups and Subscriptions. The technical requirements as well as the required permissions are minimal.
You can run the script either for your Tenant Root Group or any other Management Group.