на первой странице
<ListView ItemSelected="OnItemSelected" ... />
protected void OnItemSelect(object sender, SelectedItemChangedEventArgs args) {
if (args.SelectedItem != null) {
// replace MyType with the appropriate type for your code
MyType item = (MyType)args.selectedItem;
// pass the selected item to Page2
Navigation.PushAsync(new Page2(item));
}
}
в конструкторе Page2
MyType SelectedItem;
public Page2(MyType item) {
SelectedItem = item;
// now you can use this value to filter/etc the values
// to populate the 2nd ListView
}