Association of file extensions in the registry

HKCR\.ext  def. value refers to a HKCR\Appl.DocType
which could have key  CurVer which refers to Appl.DocType.version

In this case look for HKCR\Appl.DocType.version

To let the ShellExecute() system call find the associated executable when called with the document name, the following key should exist and be valid:
HKEY_CLASSES_ROOT\Appl.DocType[.version]\Shell\Open

a tweak

Android browser can be switched to adwanced settings mode, just type in the address bar: "about:debug".
In this mode you can change the UserAgent string to desktop or iphone in the browser's settings.
Some sites provide their mobile version only when they see the iphone UA string, not the one android sends.