var page = (Page)Activator.CreateInstance(item.TargetType);

        Label titleViewLabel = new Label
        {
            Text = item.Title,
            FontAttributes = FontAttributes.Bold,
            FontSize = 25,
            TextColor = Color.White,
            BackgroundColor = backgroundColor,
            Margin = 10
        };

        NavigationPage.SetTitleView(page, titleViewLabel);

private async void ProductView_OnItemSelected(object sender, SelectedItemChangedEventArgs args)
    {
        Product product = (Product)args.SelectedItem;
        ProductDetailPage productDetailPage = new ProductDetailPage
        {
            BindingContext = product,
            Title = product.Name
        };

        await Navigation.PushAsync(productDetailPage);
    }

protected override void OnAppearing()
    {
        base.OnAppearing();

        Label titleView = ((Label)NavigationPage.GetTitleView(this));
        // titleView.Text has "Products!!
    }