Apple Pay Test is a very simple demo project made to show an example Apple Pay flow.
I made it both to learn how to implement Apple Pay and to show potential future clients/employers that I can.
To use Apple Pay you need an active Apple Developer Account. There's some setup required before you start, Apple provide a guide here. Make sure to update the Bundle ID from com.joforsell to match your own organization identifier.
I used Apple's documentation to help set up the Apple Pay functionality. I also watched Design+Code's two part series to get an idea of how to bridge it with SwiftUI.