I have a react native app and within the app (iOS and Android), would like to provide in-app purchase. I'm selling hardware as well as subscription services associated with hardware. What do I need to do to support in-app purchase in this scenario? Do I need to enable iOS app entitlement for in-app purchase Or can I just link to our web page inside our app and redirect user to webpage to order hardware and buy services?
You can use out of the box api of in-app purchase for android and ios. But you can only use these for subscription and selling digital goods, no physical articles.
For selling physical goods as Amazon does, you must implement your own logic (server), you can use PayPal or masterpass api for incorporate secure payment method in your app for example. I recommend services like amazon web service or firebase for provisioning your server (backend).
In case of android visit this page in-app purchase for android
In case of ios visit this page in-app purchase for ios
Hope helps