I can’t add my cards or anything

See the following Apple articles:

Set up Apple Pay -> Set up Apple Pay - Apple Support

Countries and regions that support Apple Pay

Countries and regions that support Apple Pay - Apple Support (EG)

If you can't add a card to Apple Wallet to use with Apple Pay

If you can't add a card to Apple Wallet to use with Apple Pay - Apple Support

• Apple does not approve or decline cards for use with Apple Pay. If your card was declined, contact your bank or card issuer.

See -> About billing for Apple subscriptions and media products in India

About billing for Apple subscriptions and media products in India - Apple Support

See -> Payment methods you can use with your Apple ID

Payment methods you can use with your Apple ID – Apple Support (UK)

India

• Apple Account balance (from adding funds)
• Net Banking (adding funds only)
• UPI (adding funds only)

Then use / pay with your Apple Account balance, see: Add money to your Apple Account balance

Add money to your Apple Account balance - Apple Support

• Make sure you're in a supported country or region. - to use Apple Pay

How to add a boarding pass, ticket, or other pass to Apple Wallet on your iPhone:

1. Open the app, email, notification, or other communication that contains your boarding pass, ticket, or other pass.
2. Tap Add to Apple Wallet.
3. 
4. 
   
5. Follow the instructions on the screen.
6. If necessary, tap Add in the upper right corner.

If you don't see an option to add your boarding pass, ticket, or other pass to the Wallet app, contact the merchant or company that issued it to make sure they support passes in the Wallet app.

I had this problem too. Turns out my region had switched (unbeknownst to me) to the Cayman Islands, a place I’ve never been (what am I, a shady banker?). Go to settings > general > language and region. There’s a good chance that the region listed here doesn’t reflect your actual location. Once I set my location as Canada, I was able to add a new card to my Apple wallet easily. So much frustration, yet such an easy fix. Hope it works for you

I can’t add my card to my wallet