Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
You can use the Import service in the Microsoft Purview compliance portal to quickly bulk-import PST files to Exchange Online mailboxes in your organization. You may refer to the article for detailed steps: https://learn.microsoft.com/en-us/microsoft-365/compliance/importing-pst-files-to-office-365?view=o365-worldwide
Note: The PST import process checks for duplicate items and doesn't copy the items from a PST file to the mailbox or archive if a matching item exists in the target folder in the target mailbox or target archive.