Are registerDevice and registerSession the same for web vs mobile?

Since we don’t be using push notification for iOS and Android can we just have a registerSession similar to what the Web SDK offer instead of having to register device for push notification with registerDevice ?

They’re the same thing just with different name because there’s no device concept for web, it’s more of a browser session. You would need to use client.registerDeviceForPushNotification if you want to do push notifications (Push Notifications - Amity Docs)