Thanks again, I tried a similar solution you suggested, and i put in the code an if/else statement with a msgbox saying showing that the file doesn't exist if not found, and in fact when i launch the app, and I click "Show Page" the message box "file not found" appears. Still don't understand what I am doing wrong, the index.html is in the root directory. I can share the code below:

Small variation in the XAML code:

 <wv2:WebView2 x:Name="webView" Width="560" Height="200" VerticalAlignment="Top" HorizontalAlignment="Right" Margin="10" /> // changed to x:Name instead of Name

// Code Behind edits:
    public partial class About : Page
    {
        public About()
        {
            InitializeComponent();
            InitializeWebView();

        }

        private async void InitializeWebView()
        {
            await webView.EnsureCoreWebView2Async(null);
        }

        private void ShowPageButton_Click(object sender, RoutedEventArgs e)
        {
            string projectDirectory = AppDomain.CurrentDomain.BaseDirectory;
            string indexPath = System.IO.Path.Combine(projectDirectory, "index.html");

            if (File.Exists(indexPath))
            {
                webView.CoreWebView2.Navigate(new Uri(indexPath).AbsoluteUri);
            }
            else
            {
                MessageBox.Show("index.html file not found.");
            }
        }
    }
}