Is it possible to use polymorphism with an abstraction layer for different widgets in Flutter?

I have a set of around 8 widgets that all accept a single parameter of type X and display the content of type X in a different way. What I am trying to create is an abstraction layer that defines the structure of such a widget. Besides the structure, the abstraction layer would define a factory method to decide which implementation gets used based on an ID. The different implementations are all widgets that extend either Stateless- or StatefulWidget.

The abstraction layer would look like the following:

abstract class AbstractWidget {
final X content;

factory AbstractWidget({@required int id, @required X content}) {
  switch (id) {
    case 1:
      return Implementation1(content);
      break;
    default: return Implementation2(content);
   }
  }
 }

An implementation would look like the following:

class Implementation1 extends StatelessWidget implements AbstractWidget {
  final X content;

  Implementation1(this.content);

  @override
  Widget build(BuildContext context) {
    // Display content in some type of way
  }
}

So what I'm trying to achieve is the following:

var widgetList = new List<Widget>();
for (var item in items) {
  X content = fetchContentFromAPI();
  widgetList.add(AbstractWidget(content: content, id: item.id));
}
return Column(children: widgetList);

This would not work because the AbstractWidget isn't technically a Widget-type, even though it can only return instances of either Stateless- or StatefulWidgets. If anyone knows a better way of implementing my structure, it would help me a lot!