Great question. The short answer is no, but MOST of them do. Longer answer: All the countries should. As far as cities, there are currently just under 110,000 with a WikiData ID. GeoDB obtains the correlation from WikiData itself whenever the given WikiData entity has a GeoNames ID property. The situation should get even better with time as WikiData matures. You as an individual contributor can also manually go into WikiData and propose an edit to any city entity to include the correct GeoNames ID. GeoDB refreshes its data daily and should pick up your change the next day, assuming it’s approved. Thanks for your question!