Flutter is still a developing ecosystem. Even though it is backed by Google there is no great community(its growing, but not complete).
For example I wanted to build a book reader for Mobile.(I don't use ionic so...) React Native is the obvious solution.
But the PDF parser or epub parser is not available in dart-lang(which flutter uses)
Companies or agencies with experienced developers or someone who can write everything from scratch, Flutter is your optimal solution. Because its performance is awesome(compared to react-native).
For Beginners React-Native or Ionic and Xamarin for C# devs.
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