City parent in a third floor walkup. A true one hand fold means you can close and open it while your other arm is busy and and it locks itself so you can grab the frame and go which, yeah in a store I keep one hand behind my back, fold it in a single motion, then lift and walk the length of the aisle. If it tilts weirdly or bites your fingers, pass.
Make sure it stands on its own when folded so you can set it down without it flopping over. Try opening it with one hand too, some make you fumble a second latch and that ruins the flow. Take it to a corner and do a few pretend curb hops with it folded to see how it balances in your hand. If you feel strain after a minute, it is not light enough for regular stairs. Works one handed.
