This seat straps to your carry-on luggage and allows a young child to sit strapped in throughout the airport. It's called a Ride On Carry On (check out info and reviews on Amazon). We used it twice to and from Germany; like new! - its headrest turns into a tray table for the child to eat on or color. It allows you to pull your carry-on alone without a stroller in tow.
It sells for $120 on Amazon
Call or text Rachel: 801-821-2562; we live in New Baden