I'm building website (online shop) using Shopify in a headless manner. I'm using Storefront API to fetch products, create and modify checkouts and so on... The problem begins when I try to complete checkouts. To do that I'm using checkoutCompleteWithTokenizedPaymentV3 mutation and checkout.com as payment provider. The mutation returns 200 status code, but when I check the errorMessage on payment attached to my checkout I get the following message:
"There was an issue processing your payment. Try again or use a different payment method."
and my checkout appears in "Abandoned checkouts". I suspect that my app doesn't have sufficient permissions to request payment capture, so I requested "Custom Storefront Payment Processing" (I haven't received any answer yet), but there was a note in the form that web applications do not qualify.
I went through the documentation/tutorials but the informations regarding custom checkout are super misleading and inconsistent.
I'm perfectly aware that the suggested and recommended approach is to use checkout's webUrl field to redirect user to Shopify's checkout page but that's not what I'm looking for.
I would like to get concrete answer on the question if entirely custom checkout can be implemented on my website using APIs without having to redirect user to Shopify checkout page.