Hello Nishit i have personaly tried to follow your instructions from #14848
and so:

1) installed FCM Push Notification from WP
2) Logged in to Firebase and android account settings and found multiple options and snippets in Node, Java, Pyton not sure whcih i should use and where to put.
so i have many questions about how to hook it.\
a. I checked Android settings but there is IOS settings too how to hook them both?
b. I also checked the FCM Push Notification from WP settings page and it has got multiple fields to feelout not sure how to make it correctly.

So i have been trying to help yopu our with this to get this work done without hiring any one else.
So if you send me very clear step by step instructions i will try to make it myself.
Alternatevely we will need to look at the option #14855.

Kind regards Andrey