How do I add products to my app?

You don’t. 🙂

Your app is always at live sync with your WooCommercer store. You add a product to WooCommerce, your app will have it instantly. You remove a product from WooCommerce, your app will remove it.

On every screen of your app (products, categories, etc.) your app will get all the data from WooCommerce store live! Therefore you do not have to worry about adding products separately to your app.