Problem in designing software using strategy pattern

I am currently implementing a small soft, I want this soft work on Mac Os and Window Os, so I want use GLFW for mac environment and Window API for windows environment (I know GLFW is cross platform but that's not the point..)

My problem is a design implementation problem: I have created a windowManager class that keep an instance of a Window class. This Window keep an instance of an objet that is PatternWindow , PatternWindow is a interface. I have a objet PatternGLFW3_VULKAN that implement PatternWindow. this PatternGLFW3_VULKAN have an instance GLFWwindow * _window, and PatternGLFW3_VULKAN initialize _window with glfwCreateWindow(...).

class Window
{
public:
  somefunction(...)
  initializePatternWindow(unique_ptr<PatternWindow>&& patternWindow)
private:
  unique_ptr<PatternWindow> _patternWindow;
} 

class PatternWindow
{
public:
  PatternWindow();
  virtual ~PatternWindow();

  virtual void initialize() = 0;
  virtual void destroy   () = 0;

};



class PatternGLFW3_VULKAN : public PatternWindow
{
public:
  PatternGLFW3_VULKAN ();
  ~PatternGLFW3_VULKAN();

  virtual void initialize();
  virtual void destroy();

  const GLFWwindow& getWindow() const {return *_window;}

private:
  GLFWwindow * _window;
};

My question is about the getWindow() function in my PatternGLFW3_VULKAN class, how I can create a virtual getWindow() function in my PatternWindow class in order to get my GLFWwindow* window of the PatternGLFW3_VULKAN in run time if I am on Mac Os environment, I can create a virtual function GLFWwindow& getWindow() in my PatternWindow, but if I run my soft on Window environment , the type GLFWwindow of the virtual function getWindow() of the patternWindow class won't be correct...

How can I do in order to have a virtuel getWindow() in PatternWindow my that return GLFWwindow or a instance the Windows API screen in run time ?