Do you want to achieved like this screenshot?

If so, you can add the <Grid RowSpacing="-10" > directly, It will decreate the gap between the two rows of grid

1. You (and your hosting provider) are responsible of securing your API, it has nothing to do with ASP.NET WebForms or WebApi. Although ASP.NET Core MVC/WebApi is the recommended framework for any .NET web development nowadays, WebForms is still supported by Microsoft and still works.
2. Shared hosting means you can't access to the VM, so it will probably not work, as the machine needs to have some IIS modules installed for .NET Core apps to work, check with your provider, maybe they installed the required IIS modules. Still you can host your WebApi project for free on Azure. as long as there's not lot of traffic to your API.

BUT, as @ClintStLaurent said, you have to let go off WebForms (and WinForms if you're still doing it). Time to learn the new technologies, or else in few years, you will find yourself so behind it will be impossible for you to catch the train again.

You can create a subclass of UITableView or UIScrollView and rewrite the method LayoutSubviews

public class MyTableView:UITableView
    {
        public override void LayoutSubviews()
        {

            foreach(UIView view in Subviews)
            {
                if(view.IsKindOfClass(new Class("UIImageView")))
                {
                    view.BackgroundColor = UIColor.Red;
                }
            }

            base.LayoutSubviews();
        }
    }

And in CustomRenderer

protected override void OnElementChanged(ElementChangedEventArgs<ListView> e)
{
   base.OnElementChanged(e);

   if(Control!=null)
   {
        SetNativeControl(new MyTableView());
   }

}

You'd have to write your own custom framework that looks for ContentView's that implement an interface etc and then call the cleanup.

Just for your information, Prism does this out of box, just implement IDestructible in ContentView's and their Viewmodels that are contained in the page and it's all taken care of for you if you autowire the contentviews

<Components:ActiveOrders
            Grid.Row="0" Grid.Column="1"
            mvvm:ViewModelLocator.AutowirePartialView="{x:Reference RootPage}" />
<Components:OrderHistory
            Grid.Row="0" Grid.Column="2"
            mvvm:ViewModelLocator.AutowirePartialView="{x:Reference RootPage}" />

To answer your question, if you use Prism, yes, there is a better way, otherwise you'd have to roll your own. As it is, what your doing will do the job fine.

I have managed to find my template items by the name with the following code. You have to call VisualTreeHelper.GetTemplateChild<%TypeOfTheItem%>(this, "nameOfTheItem") after the InitializeComponent() method in the constructor of your templated control.

using System.Collections.Generic;
using System.Reflection;
using Xamarin.Forms;
public class VisualTreeHelper
{
    public static T GetTemplateChild<T>(Element parent, string name) where T : Element
    {
        if (parent == null)
            return null;
        var templateChild = parent.FindByName<T>(name);
        if (templateChild != null)
            return templateChild;
        foreach (var child in FindVisualChildren<Element>(parent, false))
        {
            templateChild = GetTemplateChild<T>(child, name);
            if (templateChild != null)
                return templateChild;
        }
        return null;
    }
    public static IEnumerable<T> FindVisualChildren<T>(Element element, bool recursive = true) where T : Element
    {
        if (element != null && element is Layout)
        {
            var childrenProperty = element.GetType().GetProperty("InternalChildren", BindingFlags.Instance | BindingFlags.NonPublic);
            if (childrenProperty != null)
            {
                var children = (IEnumerable<Element>)childrenProperty.GetValue(element);
                foreach (var child in children)
                {
                    if (child != null && child is T)
                    {
                        yield return (T)child;
                    }
                    if (recursive)
                    {
                        foreach (T childOfChild in FindVisualChildren<T>(child))
                        {
                            yield return childOfChild;
                        }
                    }
                }
            }
        }
    }
}

 string photos = Convert.ToBase64String((byte[])reader["Photo"]);

Add a new property in your mode and create binding it with the image .

public ImageSource Photo
    {

        get
        {
            byte[] bytes = Convert.FromBase64String(PhotoSource);
            MemoryStream ms = new MemoryStream(bytes);
            ImageSource s = ImageSource.FromStream(() => ms);
            return s;
        }
        set
        {

        }
    }

You could do this with custom renderer , refer https://stackoverflow.com/a/56555965/8187800, i complete the solution .

[assembly: ExportRenderer(typeof(Picker), typeof(MyPickerRenderer))]
namespace FormsApplication.Droid
{
    class MyPickerRenderer : PickerRenderer
    {
        public MyPickerRenderer (Context context ) : base(context)
        {

        }

        private IElementController ElementController => Element as IElementController;
        private AlertDialog _dialog;

        protected override void OnElementChanged(ElementChangedEventArgs<Picker> e)
        {
            base.OnElementChanged(e);

            if (e.NewElement == null || e.OldElement != null)
                return;

            Control.Click += Control_Click;
        }

        protected override void Dispose(bool disposing)
        {
            Control.Click -= Control_Click;
            base.Dispose(disposing);
        }

        private void Control_Click(object sender, EventArgs e)
        {
            Picker model = Element;

            var picker = new NumberPicker(Context);
            if (model.Items != null && model.Items.Any())
            {
                picker.MaxValue = model.Items.Count - 1;
                picker.MinValue = 0;
                picker.SetDisplayedValues(model.Items.ToArray());
                picker.WrapSelectorWheel = false;
                picker.DescendantFocusability = DescendantFocusability.BlockDescendants;
                picker.Value = model.SelectedIndex;
            }

            var layout = new LinearLayout(Context) { Orientation = Orientation.Vertical };
            layout.AddView(picker);

            ElementController.SetValueFromRenderer(VisualElement.IsFocusedProperty, true);

            var builder = new AlertDialog.Builder(Context);
            builder.SetView(layout);
            builder.SetTitle(model.Title ?? "");
            builder.SetNegativeButton("Cancel", (s, a) =>
            {
                ElementController.SetValueFromRenderer(VisualElement.IsFocusedProperty, false);
                // It is possible for the Content of the Page to be changed when Focus is changed.
                // In this case, we'll lose our Control.
                Control?.ClearFocus();
                _dialog = null;
            });
            builder.SetPositiveButton("Ok", (s, a) =>
            {
                ElementController.SetValueFromRenderer(Picker.SelectedIndexProperty, picker.Value);
                // It is possible for the Content of the Page to be changed on SelectedIndexChanged.
                // In this case, the Element & Control will no longer exist.
                if (Element != null)
                {
                    if (model.Items.Count > 0 && Element.SelectedIndex >= 0)
                        Control.Text = model.Items[Element.SelectedIndex];
                    ElementController.SetValueFromRenderer(VisualElement.IsFocusedProperty, false);
                    // It is also possible for the Content of the Page to be changed when Focus is changed.
                    // In this case, we'll lose our Control.
                    Control?.ClearFocus();
                }
                _dialog = null;
            });

            _dialog = builder.Create();
            _dialog.DismissEvent += (ssender, args) =>
            {
                ElementController?.SetValueFromRenderer(VisualElement.IsFocusedProperty, false);
            };
            _dialog.Show();


            Android.Widget.Button btnOk = _dialog.GetButton((int)DialogInterface.ButtonPositive);
            btnOk.SetTextColor(Android.Graphics.Color.Green);
            Android.Widget.Button btnCancel = _dialog.GetButton((int)DialogInterface.ButtonNegative);
            btnCancel.SetTextColor(Android.Graphics.Color.Black);

        }
    }
}

Agree with your answer in SO, SkiaSharp is a good choice.

The newest version of VS for mac is 8.x.x .So you can firstly update the IDE .

@AtanasAngelov
DependencyService can achieve your function. DependencyService can find the right platform implementation of defined behavior in platform-specific projects and allow shared code to access the native functionality.

Check the tutorial:
https://docs.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/dependency-service/introduction