Push Notification From Nodejs REST Api to android mobile device

I am working on an Ecommerce application which is deployed on the web using MERN and on mobile using Android SDK. The android application is using the REST Api made with node, express and mongo. The issue is I am unable to find a way to send push notifications to mobile devices from the node backend. I don't want to use third party push notification services such as pubnub or firebase FCM etc. On the web application I am using service worker on the client side for push notification which was easy to implement, but on the mobile side it is turning out to be a bit difficult and every where on forums and articles FCM, GCM or pubnub etc are being used. Is there any way to avoid these services and make my own custom mobile push notification service using node REST Api I have made? If so how?