Outlook add-in PST Import Service
Improve the PST Import Service by creating an Outlook add-in that can be deployed to users. The users could use the add-in to select which of their PST's should be uploaded. The add-in would then use a service account / service principal which uploads the PST to Azure blob storage SAS URI, and an import job created automatically.
This all seems quite possible. It would be better than dragging/dropping PST items manually in Outlook. The add-in might need to include Azcopy.exe somehow, etc.