The next question is "Is your app paying in the app?" In order to create a new application Make a prototype that actually moves with minimal cost Since it is necessary, I will make it for free first.
You can use Google Pay on your Android phone to make in-store purchases at any compatible payment terminal.
With iPadOS 26, Apple added a dedicated Phone app to the iPad for the first time. It doesn't turn the tablet into a standalone phone, but it gives you access to your iPhone's line through Continuity.