My use case: as a third party platform I want to have access to my merchant's transactions, as soon as possible.
I could probably ask my merchants to go to their admin panel and set their IPN URL to my service but I'd prefer the authorization experience to be more user friendly. So instead, I've been trying to get authorized to set up webhooks for the merchants. From what I checked it is possible to ask third parties for authorization with the https://uri.paypal.com/services/applications/webhooks scope and get a refresh and access tokens to the REST Api. But when I try to use those credentials to create new hooks, the hooks I created for my application and not for the merchant's. I tried using PayPal-Auth-Assertion header instead of the merchant's access token but again, the hooks were being created for my app only. Is it possible to do what I'm trying to do? Is it possible to get authorized to create webhooks for some third party account?
If it's not possible, do you have some suggestions about different methods I could use? I've looked briefly into polling the reporting/transactions API but it can have couple of hours of delay.