How to get pushTokenUpdates when starting a Live Activity via Push Notification

I'm trying to build a Live Activity extension. I can successfully start my live activity via push notification. The problem is, when I start live activity from my app, I can get pushTokenUpdates since I control everything and run the for loop that gets pushTokenUpdates. But the code that gets pushTokenUpdates isn't called when I start live activity with push notification since system starts it automatically (maybe it is called, but I don't know when and where).

Where am I supposed to get pushTokenUpdates when I start Live Activity using push notification to send them to my server?

The relevant code is below:

for await data in activity.pushTokenUpdates {
    let token = data.map { String(format: "%02x", $0) }.joined()
     Logger().log("Activity token: \(token)")
     // send token to the server
}