Wide hands on a wobbly dome stretch the chest deep.
Wide hands load the chest more, keep your core tight so the dome does not tip.
Setting your hands well outside shoulder width lengthens the arc your chest works through, loading the pecs deeper in the stretched bottom position while the dome shifts under your wide grip. Your shoulders take a larger share in the wide position and your triceps close out each press. It earns a place when you want to bias the chest hard in a push-up, with the unstable platform keeping every rep honest.
The wide hand position reduces how much the triceps can contribute and lengthens the stretch across the pecs, so the chest does a bigger share of the work. On the dome, that stretch position also becomes a stability challenge.
If your shoulders pinch at the bottom or the dome starts tipping side to side, bring the hands in. Well outside shoulder width is the target, extreme width just strains the shoulders for no extra chest.
Lower until you feel a real stretch across the chest, keeping control of the dome the whole way. Depth you cannot stabilise on an unstable surface is depth you have not earned yet.
