We would like to hear your opinions about Push notifications for Android apps.

I'm currently using Firebase to send push notifications to my Android app.
There is a problem that we cannot respond when we want to send tens of thousands of items at once.

Of course, if you adjust the number of requests on the server side, you can send it, but
If I want to send push notifications to all users in one request
What kind of implementation method can be considered?

After all, is it better to insert a system such as AWS before sending a request to Firebase?

I would appreciate it if you could teach me.