Spoiler: This is going to be a little bit harsh, so don't continue on reading, if you're already having a bad day!
Well, there's one good point, at least good for you, about this article. You can copy & paste the whole text, replace "Flutter" with "NodeJS" and publish another story of the same type with the aim of collecting applauses and views.
And, after a week or so, depending on your consistency of publishing, you can do the same but with "Laravel".
You get my point? No? Let me explain.
Therefore, show a little bit more respect to them.
Judging from your claim, that you got your app up and running within one week - for both platforms (!!), while in the process of learning Dart & Flutter (!!), (while still feeling the urge to brag about it) , brings me to the conclusion, that you're simply not experienced enough, to be taken seriously. This brings me to my next point.
Correct me if I'm wrong, but as far as I understood, your app parses XHTML (actually, no one calls it like that anymore, it's just HTML) and based on that HTML you either place widgets somewhere in your app, or display a WebView.
This is simply NOT considered best-practice.
There's JSON for such kind of data transmission. And yes, that would require you to rebuild your server-side code, but obviously, you wanted to go the short route and just use what's already there, HTML.
As a result: This is not where Flutter failed, it's where you failed!
If you wanted to go the short route, you could've just simply built a native app, and put everything into a WebView, and spare yourself the non-standard hassle.
But no, instead, you choose to go with the Flutter trend. First to claim, you've built a Flutter app (for something it was never intended to be used for), and secondly to publish an article about Flutter - since everyone is publishing articles now - which goes beyond the "how to [whatever claim] in Flutter🔥" nonsense, but in fact leverages another type of nonsense.