I’d need much more context to say for certain, but it sounds like Shopify isn’t really the solution you need. If you have the skills to build a basic app for selling your product you just need a payment processor. I’d recommend Stripe, they have both HTML5 and React components that you can mostly drop into your app and add the payment processing without much effort. Mostly just creating an account and doing a little work to wire things up.
Is there a reason why Shopify is a good choice for selling your product? Shopify seems better suited to stores with many products/variants in general.