Update in January 2021. There are still no visits planned for the nearby future. You have to fly to LA to file an application in person. You can also fly to Vancouver, BC, but you cannot currently drive there from Seattle. To schedule a visit, use the online reservation system
While American citizens cannot enter the EU countries, you can fly to Europe on a different passport, such as a Polish one. There are two ways to do it: on regular flights or “rescue” flights. For regular flights, it’s the usual. You can book a flight on a regular airline