While PayPal refers to these as "smart payment buttons", Shopify offers "dynamic checkout buttons", which are quite similar. Dynamic checkout buttons are displayed on your product pages and dynamically change to reflect the customer's preferred accelerated checkout method, which is quite often PayPal. Much like smart payment buttons, dynamic checkout buttons offer the customer the ability to pay with PayPal directly from the product page. However, while PayPal's smart payment buttons also display "Credit or Debit" as options, Shopify's dynamic checkout buttons instead include a "More payment options" button, which will take customers directly to the Shopify checkout, where they can proceed with a credit card transaction.
If you are still interested in adding the PayPal smart button, I would advise reaching out to a Shopify Expert to see if anyone can carry this out, as this does require some code editing. I trust this helps, thanks!
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