IAP vs Paypal

We are developing the mobile application for selling products. We have researched the payment policy and found out that in-app purchase is applied for digital product / service and there may be a charge (15-30% per transaction).

So, if our mobile app sells both digital products and physical products, could we integrate Paypal to our app? And, how can we write API in this case?
If the 'digital product' is used within your app you must sell that digital product using IAP. The physical products can be sold using PayPal. If the user desires to purchase the digital product they would be sent to IAP software. If they desire to purchase a physical product they would be sent to PayPal software.
Thank you for your response. So, what if user's order includes both digital products such as (subscription) and physical products. Is there anyway to pay on one platform? Or our customer need to pay separately?

How did you end up handling this case?
IAP vs Paypal
 
 
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