stop, linger, appearance, figure, bearing
佇 centers on a person pausing in place: stopping, lingering, or standing still. The senses of appearance, figure, and bearing extend naturally from the image of someone standing in a composed, visible posture.
佇 combines 亻 (person) with 宁, which likely contributes the sound and may suggest standing or stopping. The exact historical development of 宁 in this character is uncertain.
A person 亻 beside 宁, which looks like a roof over a nail, suggests someone pausing under shelter. Picture a traveler lingering at a roadside rest stop, standing still and taking in the view.
For チョ, imagine a person lingering at a crosswalk, waiting for the 'cho' sound of the pedestrian signal: cho -> チョ, and they stop and stand still until it changes.