The data used for Microsoft 365 usage reports comes from the Microsoft Graph. You can anonymize the data to replace references to user, group, and site names with system-generated values to protect user privacy. This works, but it reduces the usefulness of the reports by a large degree, so you should be prepared to switch to show full user data sometimes.
PowerShell hash tables are very efficient at retrieving data, which is just what’s needed when thousands of Office 365 accounts need processing. Our script to analyze usage data extracted from the Microsoft Graph was turbo-charged when we replaced list objects with hash tables, all of which makes it much easier to identify underused Office 365 accounts and save some money on licensing spend.
Several updates are available for the standard usage reports in the Microsoft 365 Admin Center. One helps Office 365 tenants understand the changed user activity profile due to remote working. Another gives views of user activity across the complete tenant. The updates are useful and interesting, but an ISV product will do a better job of analyzing and reporting the same data.