Hi, thank you for the question. Understand how notification works is the easiest part, the hard one is to know how to use it 😃.
- Do we send push notifications to both devices?
I think this really depends on the app scenario. Think about what the notification is for. Does the user need to see it on both devices?
- If a user unsubscribes from Desktop should we stop sending to Desktop but continue on Mobile?
The unsubscription is a voluntary action, this means that the user typically has to click a button. As a user, the best experience for me would be: when I click the button, the app asks me: “Should we continue sending notifications on the other device?” or something like that. I know that this would take extra development, so maybe an easier solution is to stop sending the notifications just to the Desktop device.
- If a user registers on another phone ideally we should detect the device and overwrite the subscription.
Again, if in doubt ask the user. If this takes time to be developed, go ahead with the acceptable minimum effort that provides more value to the user.
How many subscriptions/devices you have to keep? Once more, it depends on the content and the type of notification/app itself. Sometimes you want to keep only one device type, some other to keep both. For example, if you have 2 mobile phones: your personal one and you work one, maybe in this case you want to keep sending the notification to both of them. Or maybe not 😃.
In my opinion, the key point is: think about the best experience for your users. Next, think about what the notification is intended for.