Getting list of all site collection admins for OneDrive
Currently, there no way to fetch a list of all site collection admins of all OneDrive account. The only way to check it is by going to Admin Portal and checking it for each and every user.
PowerShell (Set-SPOUser) allows to add new site collection admins to SharePoint sites and OneDrive. However, Get-SPOUser doesn't get the site collection admins unless the admin account is already site collection admin on the OneDrive.
It would be great to have some way for admins to fetch a list of all site collection admins either using script or GUI.
Alex C. commented
We're running into this issue as well. I'm very surprised that there's no way to do this through PowerShell, and that Office 365 doesn't provide a reporting tool for admins. Either option would work for us. I may have to result to granting myself access, pulling the list of admins, and then removing my access. That seems inefficient and error prone.