I have made a food ordering app (using flutter) for my college and it is currently in production.
I have used a payment gateway (razorpay). Everyone uses google pay to place their orders. In android there is a gpay button that open google pay within the app and the payment is done super fast. But in ios there is no such button and the user has to enter the upi id, then open gpay themselves, and finally when they return back to the app, the payment gets successful after waiting for minutes.
I have tried a lot but can't seem to find a solution.