@Diesel555 thank you for your answer.
Meantime I’ve seen that the most used approaches are:
We have to build an app that has to heavily interact with a map so I think it is better to use the second solution to have the complete control of the map and to have all the features available.
You say that Ionic4 has some problems with Google Map on iOS, this could be a great problem.
We use hybrid frameworks because with them we develop an app usable on both Android and iOS, and now we have to use two different Maps APIs for Android and iOS?
So I’m starting to doubt that Ionic4 is a framework ready to develop a complex app that should be in production within a few months.