Is there a way to send push notification between 2 android devices without a server?
I found some tutorials but all of them was using the node.js for sending a notification. (Or I found that some samples that were using the firebase console for doing this)
Nope,
You need a "server" to do push notification. You can use a variety of services to do that, as you mentioned firebase is one of them. You may not need a full on server, but you need some kind of service to do that, you can't simply send notifications between devices straight away:
Some examples are:
If you'd rather use one of these services, then you'll need to configure FCM in your app, you can check how to do that in the docs. And some nice sample codes here :)
