Hi,  As per the same exploration on our side, this might be connected to some restrictions for the new integration type - via the new Payment API. Same sample script isn't working with our payment application as well. Hope this helps a bit to clarify...

HI, As per our understanding, you cannot do that. It would also make sense for us as we have local payment methods to add.  Let's see, if we get an answer from someone at Shopify. Regards,Nikita