Sales Channels are supposed to use the Checkout API to send Shopify the payment data of the customer to complete the Checkout. Unfortunately the Checkout API only allows to send credit card information and not paypal payment information. This would be very limiting. Which platform only offers credit card payments?
That's why we intend to collect the money on our platform ourselves instead of sending the payment information to shopify. This would mean, we have to create an order in the merchants shopify account without a payment. This is not possible with the Checkout Api. How does for example the Facebook Sales Channel solve this problem? They also collect the money on their platform instead of sending the payment information to Shopify.