Of course it all depends on the country being open to tourists from the USA as well as things to do being open and operational in the country. Some countries are better than others at having outdoor attractions and places that can't really close, such as free public beaches, parks without fences/gates, interesting walks and neighborhoods with nice architecture, scenery, etc. If there's concern that certain regions might close, it could be better to rent a car (except in major cities) and not make reservations in advance that can't be cancelled easily. Even if museums are open, tickets/reservations could be very hard to obtain. If restaurant capacity is restricted, attractive dinner reservations could also be difficult, although in much of France and Italy, there's a lot of outdoor restaurant/bar/cafe space. The OP would need to pay attention to evolving conditions and be ready to change plans.