Dynamic checkout: How to turn on in Pipeline
Dynamic Payment buttons were introduced in Pipeline 4. By default, the buttons are turned off. To turn on the feature use the Product page settings in your Theme Editor:
How to find your Product page settings
Then in the Product page settings, turn use the checkbox to turn the feature on:
Tip: When testing the buttons, be sure you are on an Apple Pay capable Safari browser or an iPhone to see the Apple Pay button appear. It won't appear in Chrome. In your payment settings you'll need fast checkout activated for PayPal and similar for Amazon Pay.
One nice feature about using Dynamic Payment buttons, discount codes are easier to add: