Thanks for the suggestion.Plaid Radish commented
This is a critical feature. I have dropped my OneDrive storage accounts and reverted to the free account, until Microsoft adds the ability to sync to an external drive. Cloud storage space is often used by consumers who want the peace of mind of off-site backup. For those of us who need local copies of those off-site, backed-up files, but who don't have the needed hard disk storage space to keep them on our OS drive, an external storage solution is crucial. Not being able to sync those files to OneDrive prohibits use of Microsoft's cloud services.
PLEASE, can someone push this feature forward?