In the buggy, when it’s nap time / she is looking tired I lean her back and put blanket over her. She resists a bit at first but as long as we get moving (and I called the tiredness right) then she quickly settles. Then I gradually pull the shade down a little at a time so it’s keeps pace with her dropping eyelids. If I go too fast she gets upset that she can’t see and I have to open a bit. I also often sing her nap time song, or shush, or we have a particular piece of music that really chills her out. It can take around 20mins but works. Other essential is to keep moving, relatively fast pace walking, smooth path best, in quiet location - but whatever you do, don’t stop!
https://a.co/d/baxAPhr Something like this, and maybe a portable sound machine?
I put a little breathable cover over top of the car seat and that’s usually enough to keep him from looking around/getting distracted and he’ll fall asleep after a few minutes!