Push Notification Opt Out

Hi Campaign Fam,

We're currently building a workflow (and implementing push notifications) where:

1. If a user has our app installed, we will send them a push notification
2. If a user does not have an app, we will send them an email instead
3. If the user does not have an email address (or blacklist etc) we will send an SMS

Question:
How do I know if a user has turned off push notifications to their device? I'm aware of the mobileAppOptOutMgt workflow, however it seems that this only de-registers devices that have actually been deleted, but not devices with push disabled.
I don't want to quarantine a device on delivery failure because if they turn notifications back on, then I want to be able to contact via push notification again.

Thanks!