AppsFlyer is an extensive analytics that help brands keep track of their attribution and engagement campaigns while providing a large variety of analytics.
This clientside integration will allow you to to retrieve Batch push notifications opens in the Retargeting section much like the below screenshot:
First step, enabling AppsFlyer SDK to pick up opens
By following the official AppsFlyer documentation, their SDK will be able to track push opens.
Second step, adding AppsFlyer data in the push payload
Simply add this few lines in your Batch Custom Payload to enable the notification to be tracked down by AppsFlyer SDK :