Not sure there is a direct way to get this info. Though you can try to use Adalo API as a workaround.
See the document here: Trigger Push Notifications via API - Adalo Resources.
The key thing will be using the response from the API. So, the logic might be:
user visits the screen in the app, where you have “request notification permissions” action
user answers yes or no (we don’t know it now)
in some time, you send Push notification to this user
if you get “failed” > 0, then it means user hasn’t allowed notifications
if you get “successful” > 0, then user has enabled notifications for your app. This is the info you need.
Such approach might require some testing, though it’s worth exploring from my point of view