We are about to implement klarna checkout v3 for a customer but Klarna says that the checkout implementation isn’t enough you also need to implement below API.
Are these APIs included in Litium Klarna checkout V3 addon?
Onsite messaging is totally on Java script, as you can see on their documentation, therefore the Litium AddOn does not get involved in it at all. However, to use it, you need to configure the JScript code so that the order grand total is available to Klarna. The order grand total is available in the cart in the session.