People (including me) write activities and make them unlisted instead of making them public because there are multiple hurdles one needs to clear. Having no errors and satisfying accessibility requirements seems like reasonable bar to clear and most folks are doing so anyways. This leaves classification. Would the path to making activities public be less cumbersome if one were required to mention the general topic the activity belonged to? Calculus would cover Calculus 1, 2 and 3. Algebra would cover Algebra 1 to College Algebra. Further classification could be a requirement for curation.
Would it help if the topic classification were requesting whenever a new document got created?