How to connect to Apple’s legacy server-to-server subscription endpoints (StoreKit v1) to receive real-time notifications

Our mobile app uses a specific platform for subscription management. At this time,, it's integration with Apple notifications is built around the Server-to-Server Notifications v1 and the traditional verifyReceipt endpoint. At this time, it does not support Server-to-Server Notifications v2, nor has any published documentation or resources on a custom integration path using v2. Our app is built using Flutter and we handle purchases with the in_app_purchase plugin. However, due to the limitation on the system for subscription side, we need to connect to Apple’s legacy server-to-server subscription endpoints (StoreKit v1) to receive real-time notifications and validate receipts. Could you please provide information how to do it?

How to connect to Apple’s legacy server-to-server subscription endpoints (StoreKit v1) to receive real-time notifications
 
 
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