UWP UserControl Resources Binding to x:Bind

Question

In this xaml snippet I tried to specify the ViewModel and the Locator for the x DataType to change the bindings to x:Bind, but unfortunately that doesn't work here. Why can't I simply omit the specification of Source={StaticResource Locator} and address the whole thing via the x DataType, what am I doing wrong?

    <DataTemplate x:Key="appointmentTemplate" >
        <Grid Background="White" >
            <Grid.RowDefinitions>
                <RowDefinition/>
                <RowDefinition Height="Auto"/>
            </Grid.RowDefinitions>
            <Interactivity:Interaction.Behaviors>
                <core:EventTriggerBehavior EventName="Tapped">
                    <core:InvokeCommandAction Command="{Binding CalendarUCView.GridTappedCommand, Source={StaticResource Locator}}"/>
                </core:EventTriggerBehavior>
            </Interactivity:Interaction.Behaviors>
            <ListView ItemsSource="{Binding Converter={StaticResource cellModelToEventsConverter}, Mode=TwoWay}"
                        VerticalAlignment="Top"
                        Grid.Row="0"
                        Style="{StaticResource appointmentCellListViewStyle}"
                        ScrollViewer.VerticalScrollMode="Auto"
                        ScrollViewer.VerticalScrollBarVisibility="Auto"
                        SelectedItem="{Binding CalendarUCView.SelectedAppointment, Source={StaticResource Locator}, Mode=TwoWay}">
                <Interactivity:Interaction.Behaviors>
                    <core:EventTriggerBehavior EventName="Tapped">
                        <core:InvokeCommandAction Command="{Binding CalendarUCView.ItemTappedCommand, Source={StaticResource Locator}}"/>
                    </core:EventTriggerBehavior>
                </Interactivity:Interaction.Behaviors>
            </ListView>
            <TextBlock HorizontalAlignment="Left"
                        VerticalAlignment="Bottom"
                        Grid.Row="1"
                        Text="{Binding Converter={StaticResource cellModelToDayConverter}, Mode=OneWay}"
                        Margin="4"/>
        </Grid>
    </DataTemplate>

I tryed:

     <DataTemplate x:Key="appointmentTemplate" 
     x:DataType="viewModel:CalendarUCViewModel" >

and also:

    <DataTemplate x:Key="appointmentTemplate" 
     x:DataType="locator:CalendarUCView" >

   

So usually I can do this:

    Command="{x:Bind GridTappedCommand}"

instead of that:

    Command="{Binding CalendarUCView.GridTappedCommand, Source={StaticResource Locator}}"

Or if I change the x:DataType to the View (x:DataType="local:CalendarUCView") and use in View:

     public CalendarUCViewModel Vm
     {
        get => (CalendarUCViewModel)DataContext;
     }

usually can do this:

    Command="{x:Bind Vm.GridTappedCommand}"