The Microsoft Graph SDK for PowerShell can be used for many purposes, among which is access to Azure AD account sign-in data. In this article, we explain how to use the SDK cmdlets to retrieve sign-in data for both tenant and guest accounts and report what we find. You can use the report to identify potentially unused accounts which might not need some expensive licenses, or guest accounts that are no longer used.
https://practical365.com/using-microsoft-sdk-powershell-report-azure-ad-account-sign-ins/
