How to export transactions

Here's the actual links to doing this in Apple Card (the link in the Related Article talks about ordering a plastic version of the Apple Card).

Download or export your Apple Card statements and transactions - Apple Support

https://support.apple.com/HT211236

Download Apple Card statements online - Apple Support

https://support.apple.com/guide/apple-card-web-servicing/download-statements-devd60473e47/web

I know this is available for Apple Card but I cannot find it for Apple Pay. You can only view your history, not export it in a formatted form.

How to use Apple Pay - Apple Support

For other payment methods in your Wallet App that are not the Apple Card, the transaction history is not available in the Wallet App to export. You would need to use your bank's or card issuers app or website to get all of your card's transactions. Apple Pay is just a conduit and will not store the entirely of the payment methods history only recent ones.

For Apple Card, just follow the steps linked above to get the purchase history statement.