How to send Push Notifications when the data from an API changes?

I want to create push notifications for my App and want to send one as soon as the data coming from an API changes.

How would I do it?

I can probably do it via Firebase Cloud but I’ve never done this before
Another way is to let the app keep running in the background and send native push notifications via the native plugin from IONIC.

Now, what is the best way to approach is?

That’s not how push notifications work. The notification itself has always to be triggered from a backend component.

So that’s exactly what you should do: Implement something that learns about the API changes, then tells some push API to send a notification.

I want this too. Someone has to show me how to do it. Because I don’t know.