This improvement is completed. You can check admin center - user detail screen.

Scoped admins. can manage users within their scope if the attribute is automatically synced with 365 data, but I need them to be able to add a new user, manually set the department and manager attributes. We cannot sync with other 365 data, because it is littered with inconsistent data that does not apply to our sub-unit organization. Configuration editor role does not work either.

Bringing this back to the top of the pile. I need my scoped admins to be able to update their staff attributes. Currently, this can only be done by global admin., and I can't give them that access, because they'd be able to read other manager reviews. Please, add a switch for them to edit user attributes!