Currently I don't see an option to export a list of users who have access like Member, Admin, Contributor under Manage Permissions section under settings for a premium workspace This feature is needed as there is lot of manual work involved in case one wants that list. Export to excel/csv would be a great help to all fellow developers.
If you only want to export special access users from workspaces, perhaps you can create a new idea here.
It is a place for customers provide feedback about Microsoft Office products . What’s more, if a feedback is high voted there by other customers, it will be promising that Microsoft Product Team will take it into consideration when designing the next version in the future.