The top comment on that SO post is: > It's definitely possible -- you don't have to use Firebase to deliver push notifications. You can roll out your own notif

The top comment on that SO post is: > It's definitely possible -- you don't have to use Firebase to deliver push notifications. You can roll out your own notification solution or consider a paid product such as Pushy (pushy.me) which does not rely on Firebase Cloud Messaging. Full disclosure - I am the Founder & CEO at Pushy. So clearly someone else has done it and built a business around it.