vironment Windows 11, OneDrive desktop sync client (personal, not OneDrive for Business) Windows signed in with a Microsoft account based on an outlook.com address Separate Microsoft account based on a gmail.com address, which holds my OneDrive…

Hello,

Yes, you can sign in with a different account in the OneDrive desktop client.

That is, you can have an @outlook.com Microsoft account signed in to Windows and use a completely different Microsoft account in the OneDrive desktop sync client app.

What happens is that all your files on the @gmail.com account (which is also a Microsoft account) can be accessed through the OneDrive folder, and your files and folders can be backed up and synced to this account.

Your Windows account does not affect the OneDrive account you use in the desktop client.