Page小部件可以获取数据，以及用于传递数据的回调函数，我将解释我的意思。
buildPageView应该向小部件传递额外的参数：

int data = 0;

void onDataChange(int newData) {
  setState(() => data = newData);
}

Widget buildPageView() {
    return PageView(
      controller: pageController,

      onPageChanged: (index) {
        pageChanged(index);
      },

      children: <Widget>[
        AddPropertyDescription(pageController: pageController, data: data, onDataChange: onDataChange),
        AddPropertyMedia(pageController: pageController, data: data, onDataChange: onDataChange),
        AddPropertyLocation(pageController: pageController, data: data, onDataChange: onDataChange),
        AddPropertyDetails(pageController: pageController, data: data, onDataChange: onDataChange),
        AddPropertyAmenities(pageController: pageController, data: data, onDataChange: onDataChange)
      ],
    );
  }

小部件本身应该接受以下参数：

class MyWidget extends StatelessWidget {
  const MyWidget({
    @required this.data,
    @required this.onDataChange,
    Key key,
  }) : super(key: key);

  final int data;
  final Function(int) onDataChange;
  
  @override
  Widget build(BuildContext context) {
    return FlatButton(
      onPressed: () => onDataChange(data + 1),
      child: Text(data.toString()),
    );
  }
}

我想说的是你的情况下是真正适合Provider。
下面是一个简单的演示与PageView和提供者，你可以复制和测试：

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

class ProviderPageViewDemoPage extends StatefulWidget {
  const ProviderPageViewDemoPage({Key? key}) : super(key: key);

  @override
  State<ProviderPageViewDemoPage> createState() =>
      _ProviderPageViewDemoPageState();
}

class _ProviderPageViewDemoPageState extends State<ProviderPageViewDemoPage> {
  final _pageController = PageController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('PageView with Provider')),
      body: ChangeNotifierProvider(
        create: (BuildContext context) => _DataModel(),
        child: PageView(
          controller: _pageController,
          children: const [
            _MyWidget(backgroundColor: Colors.red),
            _MyWidget(backgroundColor: Colors.green),
          ],
        ),
      ),
    );
  }
}

class _DataModel with ChangeNotifier {
  int _count = 0;
  int get counter => _count;
  void increment() {
    _count++;
    notifyListeners();
  }
}

class _MyWidget extends StatefulWidget {
  const _MyWidget({Key? key, required this.backgroundColor}) : super(key: key);

  final Color backgroundColor;

  @override
  State<_MyWidget> createState() => _MyWidgetState();
}

class _MyWidgetState extends State<_MyWidget>
    with AutomaticKeepAliveClientMixin {
  @override
  bool get wantKeepAlive => true;

  @override
  Widget build(BuildContext context) {
    super.build(context);
    // get the dataModel
    final _dataModel = Provider.of<_DataModel>(context);
    return Container(
      color: widget.backgroundColor,
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Text(_dataModel.counter.toString()),
          ElevatedButton(
            child: const Text('add'),
            onPressed: () {
              // change data
              _dataModel.increment();
            },
          ),
        ],
      ),
    );
  }
}