First of all, you need to understand why Isolates are used in Flutter. There are multiple purposes.

Why Isolates are Used in Flutter

Preventing UI Freezes:

• Moves high or expensive operations off the main UI thread

• Keeps your app responsive and jerky free while heavy computation

  True Parallel Execution:

• Allow concurrent processing across multiple CPU cores

• Each isolate runs independently with its own thread and isolated memory

  Batter Memory Management:

• Handle better memory management than traditional way.

  Background Processing:

• Handles tasks when the app is in the foreground

• Limited background processing capabilities

Limitations of Isolates

However,There are also isolates limtations

- Communication Overhead: Passing data to isolates serialization/deserialization
- No Direct UI Access: Isolates can't directly update the UI
- App Termination: Isolates don't live/survive on application termination.
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Remote push notifications
Still If you would like to use push notifications in a way even when your app is terminated or killed, you can handle push notification logic on the server side. With server-side push notifications, both Android and iOS platforms will work perfectly. so push notification will not be depend on isolate.