How to display ListView inside the ListView in Xamarin.forms

I guess you could use Listview inside a Listview as shown below.

<ListView x:Name="contactList" ItemsSource="{Binding PlatformsList}" SeparatorVisibility="Default"
             VerticalOptions="Center" HorizontalOptions="Center" WidthRequest="150">
    <ListView.ItemTemplate>
        <DataTemplate>
            <ViewCell>
                <StackLayout>
                    <Label Text="Nested List" />
                    <ListView x:Name="contactNestedList" ItemsSource="{Binding BindingContext.PlatformsList, Source={x:Reference contactList}}" HeightRequest="300" BackgroundColor="Yellow" WidthRequest="150">
                        <ListView.ItemTemplate>
                            <DataTemplate>
                                <ViewCell>
                                    <StackLayout Orientation="Horizontal">
                                        <CheckBox IsChecked="{Binding IsChecked}" VerticalOptions="Center" />
                                        <Label TextColor="Red" Margin="10,0" Text="{Binding PlatformName}" IsEnabled="{Binding IsChecked}" VerticalOptions="Center" />
                                    </StackLayout>
                                </ViewCell>
                            </DataTemplate>
                        </ListView.ItemTemplate>
                    </ListView>
                </StackLayout>
            </ViewCell>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

However, using ListView inside a ListView is not recommended. If in case, if your nested list is a defined one with only a fixed set of items, then you could use BindableLayout instead of the nested Listview. i.e. Just replace the ListView inside the parent ListView with a BindableLayout.

If in case, if you have any doubts about using BindableLayout, please check my below blog to understand more about it.

https://xdevlogs.com/2020/01/04/bindable-layout-xamarin-forms/

I hope it helps...