It's not clear how to add a text label next to a radio button.

The sample app uses radio buttons with no labels:
https://github.com/flutter/flutter/blob/master/examples/flutter_gallery/lib/gallery/example_code.dart#L148

The docs have no mentioning of labels:
https://docs.flutter.io/flutter/material/Radio-class.html

On Android you simple set the :text property:
https://developer.android.com/guide/topics/ui/controls/radiobutton.html