Can I integrate qbo with a custom app using api's, or should I explore sdk's instead?

Question for QBO Community: We are building a custom embedded Shopify app for B2B customers to manage credit limits and a rebate program. Customers place orders in Shopify using standard payment methods (card/PayPal), but we also track a custom credit balance internally in our app. This credit is not a QBO payment method — it’s a virtual balance assigned to each customer by the admin. When an order is placed, we deduct from the customer’s custom credit balance, and when payment is reconciled in QBO, we want to update the available credit in our app. Rebates are also calculated monthly (based on paid revenue) and issued as additional custom credits. My main questions: Does QBO support syncing this type of custom credit balance (non-payment, internal logic) through APIs, or should it be tracked in QBO as credit memos/journal entries? For rebates, is it better to represent them in QBO as discounts, credit memos, or custom fields? Is there a recommended best practice for reconciling these balances between Shopify (custom app) and QBO?