Question about rule 3.1 relating to payments

We're developing an app which allows users to purchase 2 types of things.

Thing 1: In-app credits, which allow users to post content. Thing 2: Physical objects which will be shipped to the users delivery address. These physical objects also include X free in-app credits.

From what I understand from the rules, Thing 1 would require an in-app purchase.

3.1.1 In-App Purchase: If you want to unlock features or functionality within your app, (by way of example: subscriptions, in-game currencies, game levels, access to premium content, or unlocking a full version), you must use in-app purchase.

Thing 2 is a bit more complicated... But I assume it means we need to use apply pay or another payment provider.

3.1.3(e) Goods and Services Outside of the App: If your app enables people to purchase physical goods or services that will be consumed outside of the app, you must use purchase methods other than in-app purchase to collect those payments, such as Apple Pay or traditional credit card entry.

However, would we be able to automatically give the users who purchase thing 2 in-app credits? Or would we need to develop a mechanism for users to apply these credits manually, i.e. with a voucher code.

I hope this makes sense.