I have been burned by Flutter for cross-application development, and after that I walked away from using it and will not use it again. You can be faster developing in Delphi and truly cross-platform. Qt for cross-platform mobile apps is ridiculous, yes you can do it... but it takes a lot more effort. Flutter is simple and easy for simple and easy applications, even then good luck when you have to update the app 6 months from now. This article lacks the fact that maintainability of the application is a key factor.