Based on the docs, it seems we need to provide Shopify with our Stripe platform account ID, then subsequently obtain our "shopify_payments_account_id" from Shopify as part of this process in order to properly tokenize a payment. However, the docs aren't clear on exactly how to go about this:
When your app creates a new checkout for a store with Shopify Payments enabled, Shopify creates a Stripe account for the merchant as part of the Connect integration, and returns the shopify_payments_account_id. You can then get a credit card token from Stripe to complete the payment.
To get access, provide Shopify with your Stripe platform account ID. You can query for this ID using the Stripe API.
Up to this point we have implemented all API requests necessary to create a checkout, add line items, shipping, etc. and have even sent a tokenized payment to Shopify via the checkoutCompleteWithTokenizedPaymentV3 endpoint. Unfortunately the payment results in an abandoned checkout with error "Failed to find requested vault card", which I assume is due to missing links between our Stripe and Shopify accounts.
In searching these support forums I have seen a variety of similar questions asked, with an equal variety of answers/solutions, though the newest ones are from mid 2020 and may no longer be accurate. Any assistance with how to go about completing this Stripe integration is greatly appreciated. Thanks!