You cannot add a Debit/Credit Card to Apple Pay if the county that you have chosen under the Apple ID does not support it. (e.g. India)
Adding Credit/Debit Cards to Apple Wallet depends on the country that you live in --> Countries and regions that support Apple Pay
However, you may add any of the following passes/tickets
Adding Boarding Passes, Bookmyshow Tickets, IRCTC (Railway) tickets, Airline Tickets, Game Tickets and Hotel Bookings are only possible if the issuer has enabled the "Add to Apple Wallet" feature for the tickets/passes issued by them. See some examples below.
The card issuer must enable the "Add to Apple Wallet" feature.
You will find this in the Card Issue Document
- Tap Add to Apple Wallet.