Custom NavigationViewItem Content

    <NavigationView x:Name="TestNavigationView" PaneDisplayMode="LeftMinimal" IsSettingsVisible="False" IsBackButtonVisible="Collapsed" DataContext="{Binding}">
        <NavigationView.MenuItemTemplate>
            <DataTemplate>
                <StackPanel Orientation="Horizontal">
                    <TextBlock Text="{Binding Name}" />
                    <Button Content="btn" />
                </StackPanel>
            </DataTemplate>
        </NavigationView.MenuItemTemplate>
    </NavigationView>