The "Secure Score Over Time" workbook has the option to view an "Aggregated score for all selected subscriptions" graph, I am wondering if it is possible to view this graph for multiple subscriptions across multiple management groups.
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 yourHierarchyMap, creates aTenantSummary, createsDefinitionInsightsand builds granularScopeInsightson 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.