How do I add push notifications to Flutter without Firebase?

OneSignal : is a free push notification service for mobile apps. This SDK makes it easy to integrate your Flutter iOS and/or Android apps with OneSignal and it’s also used in powering mobile + web push, email, SMS & in-app messages.7 Şub 2020

How to Add Push Notifications to a Flutter App using Firebase Cloud Messaging

Pushy Enterprise is a notification solution that can be self-hosted to deliver notifications in an offline environment to Android devices, without GCM/FCM . , Web developer since 1996. If you want to send a push message to either Android or Apple devices, you need to use those specifc API’s.