I want to use the Amazon SP API to get all orders where the buyer has initiated a cancellation. From what I can tell, the only way to do this is by calling their get-orders request to get all orders that have been changed in the last X hours/minutes then calling their get-order-items request on each returned order. The issue is that if we do that in 30 minute increments, we are making well over 100 API requests every 30 minutes to Amazon just to see if there was a cancellation. Due to performance concerns, this is not feasible.

I have also seen that they have their Notifications/Subscriptions system, which seems like a fancy way to say webhook, but we don’t yet have any webhook server set up on our end as the seller.

Is there an easy way to get just the buyer-initiated cancellations via SP API, or do we either have to do webhooks or call a bunch of APIs?