Device open's the provided PDF URL with the Device Browser, and style it to look like it's inside the app. making use of Xamarin.Essentials

OpenPdf.cs

using Xamarin.Essentials;

public Task OpenPdf(string url, BrowserLaunchOptions? browserLaunchOptions = null)
{
  return MainThread.InvokeOnMainThreadAsync(() =>
  {
      var currentTheme = (BaseTheme?)Application.Current?.Resources;

      if (currentTheme != null)
      {
          browserLaunchOptions ??= new Xamarin.Essentials.BrowserLaunchOptions
          {
              PreferredControlColor = currentTheme.NavigationBarTextColor,
              PreferredToolbarColor = currentTheme.NavigationBarBackgroundColor,
              Flags = BrowserLaunchFlags.PresentAsFormSheet
          };
      }

      return Browser.OpenAsync(url, browserLaunchOptions);
  });
}