with 0% forrest
Nauru - clearly more than 2% forest, here are also some photos from the ground
San Marino - mostly houses and farmland, but also plenty of trees in between and also a few larger patches
Monaco - dubious IMO, there is apparently some steeper land with trees, but I don't think it reaches 1.88% without counting the parks ...
Vatican - it does seem to include also some forest. Wikipedia says: Today's Vatican Gardens are spread over nearly 23 hectares (57 acres), they contain a variety of medieval fortifications, buildings and monuments from the 9th century to the present day, set among vibrant flower beds and topiary, green lawns and a 3 hectares (7.4 acres) patch of forest.
If you did that here, based on the FAOSTAT data for 2020, then ~0.284% of the Kingdom of Denmark is forested. 836000 square miles of land can't just disappear for these quizzes