Turtle One by Nuna

Keep in mind that on some flights they will not let you install a car seat even if it’s FAA approved and the airlines allow it. Bring a cover in case you have to check it at the gate. Check your car seat to see if it’s easier to install on the right or left side of the plane (usually right is easier). I’ve traveled with my baby in the Turtle One car seat and had no issues—way better than the flight where he was on my lap. The Graco Extend to Fit is a nightmare to haul around and install. This is all really dependent on your car seat and if you can afford an extra seat and easily install your car seat without holding up the people behind you and sweating a ton (they don’t always let little babies go on first). I usually fly delta and Alaska

Nuna makes an infant car seat that has isofix built right into the seat (no separate base needed). It’s designed for people in your situation. We don’t have a car either and a lightweight Nuna model is what we use, but I wish we had the newer one with Isofix anytime I try to remember how to put it in a car with the seatbelt With our first (height of COVID ) we had a rental car and when we asked the hospital to check whether we’d strapped our baby in correctly before we left they looked at us kinda funny but found somebody to take a quick glance. With our second we took the U Bahn home.

I don't have the Doona, but I have a full-size stroller (Bugaboo Fox) + another small travel stroller for the car (Bugaboo Butterfly), and I think this setup was the best option for my lifestyle (heavy daily use of stroller in an area with terrible sidewalks and snow, small car). We did have an infant car seat that connected to both strollers (Turtle One, I think - we chose it simply due to compatibility with both). I think you'd get more value/use out of two strollers + car seat that connects to both, as the Doona is really limited in usability past a certain age. With a travel stroller, you can get most of the benefits of a Doona, and later switch to using the stroller without a car seat.

We have the Nuna Turtle - little on the heavy side but a great carseat. Compatible with the bugaboo kangaroo

Then you’re going to want a newborn car seat if you want it to work with a stroller. Figure out what stroller you like and then get the car seat that works with, not the other way around. You’ll only be using this newborn seat for less than a year but using the stroller for much longer. We went with Nuna car seat and it’s been fine but that’s only because that’s what worked best with our bugaboo stroller.

The Noona is probably the best car seat that turns into a stroller - it’s an all-in-one. So you don’t have to worry about bringing along a separate stroller. It is great for the first year or so. And the Noona is stroller is small so you can easily bring it to wherever you’re going without it being a hassle. The ones like Uppababy Vista are good too, but it requires you to bring a separate stroller that you can click the car seat into. But once the kid outgrows the infant car seat, the stroller is just a large stroller and doesn’t really have any major benefits over any other stroller. I’ll say this - we used the Uppababy system for our first two kids then did the Noona for our third - and I really wish we had gone for the Noona in the first place.

I started with the Nuna Mix as a travel system but it was so massive. If I had another baby I’d get the Doona car seat and stroller and as they age out of that get another stroller small enough to fit on an airplane for when we travel.