Thanks to everyone for your feedback and votes on this item. We’re working through a couple of options and hope to have more information shortly. It’s a very difficult problem to solve since group membership is consumed across many different aspects of Microsoft 365. Thanks for your patience and keep the feedback coming!
An error occurred while saving the commentValentijn Scholten commented
We just ran into this issue after converting our admin accounts to b2b/guest users connected to our main Azure tenant. Since b2b users can be made global admin in Azure, it would be beneficial to also be able to make them admin in O365/Exchange/OneDrive/etc.