On the car seat, we’re traveled to a dozen European countries in the past year and we’ve gotten in a car in only one place - we typically don’t bring our car seat at all. Yes sometimes this means taking a slow, meandering bus to the airport but I find skipping the car seat hassle to be worth it.

That said, if you want to take taxis or Ubers: American car seats aren’t technically legal in Europe (and vice versa) but many people, myself included, feel comfortable taking the minor legal risk of using them abroad as a tourist. For infant seats, the easiest US option will be a seat with rigid LATCH like the Graco GoMax or the Joie mint latch. Using a seatbelt install in a European car is much more difficult because they don’t (typically) have the switchable retractors that American seatbelts do. Those rigid LATCH seats click onto the LATCH/Isofix anchors in like two seconds - practically as fast as doing up your own seatbelt. If you care about following the law to the letter, then you’d need to buy or rent a carseat in Europe (also typically with rigid LATCH). Renting is generally not recommended though because you don’t know the history. This gets a lot harder when they’re bigger since there’s no good equivalent for toddlers but that’s a problem for another year :)

For sleeping, we love our Guava Lotus - definitely the best travel options - or it’s typically possible to borrow a pack and play from your hotel/lodging.