Hello, this is Eric. I'm currently using Shopify to run my online store. Recently I have an internal system that allows customers to custom made something and build an unique SKU. I would like to know is it possible to call Shopify API to insert the SKU into Shopify inventory for check out and payment?
Yes, you could insert the sku as a product or as a variant on an existing product - this would have to be done by your app trough the admin rest or graphql apis. If you don't want to create the item then you could just create draft orders trough the api (with custom line items) and just send your customer the checkout link for payment.