As to your first statement, I have found that to be correct aswell. My current solution includes, as it has to, external storage.
On to your actual question, it is possible via the Insights API you've found yourself. Rather than moving on from page_fans_city (because it returns no results), you should find the issue. Most likely, you're using a User Access Token without the scope manage_pages
, which prevents it from becoming a Page Access token. You should also include read_insights
. Read more here. For further information about the object/insights
go here.
Hope this helped.