I’ve got a branch in good shape that allows a group to review items in a particular category. I will likely merge it early next week so people can start to try it out.
Since it’s new and somewhat experimental, it’s hidden behind a site setting enable_category_group_review. If you enable it, you can pick a group under category settings:
Members of that group will see the count of reviewable items in the header just like staff would, and can enter and review the content accordingly.