Subscription for Mac apps delivered outside of the App Store

Hi all, a tricky question about subscriptions.

We are developing an app that we want to deliver outside of the App Store.

The app has subscriptions to extend the service that we are building.

We are trying to understand if we can use the IAP for Mac apps using StoreKit 2.

We know that to create subscriptions or IAP in general we need to create an App on App Store Connect and after, create the IAP inside this App Container. In the case of Apps delivered outside the Mac App Store the App itself will never be submitted.

So the question is: how can we achieve this?

P.s. At the moment the App exists only on Apple Platform, so we don't need to manage other payment systems.