> Regarding Flutter [...] none of the devices I own was able to launch the application.

Is it still the case that none of your devices are able to launch Flutter Galler App? In an unfortunate coincidence the build that was published to Play Store right before the Dart Summit was flawed and declared that it is incompatible with most of the devices except for latest generation ones. This was rapidly fixed - but fixed build did not get into the Play Store on time.