OP mentions the Provider package [1] wasn't around when they did the Flutter version. That is really too bad, because it is absolutely the best way to manage state in Flutter. It makes things so much easier and cleaner than the other methods.

[1] https://github.com/rrousselGit/provider

Edit: I probably would have even gone back and refactored the app to use Provider before publishing the article. =) That would have been a nice additional bit of information for the reader.