The Wikipedia description of the Factory Method pattern is not correct. The objects which are created with the factory method implementation do not implement the factory method.
...'the interface for creating an object' is the abstract class Pizza(correct?)...
No. The PizzaFactory object has the implementation of the interface for creating Pizza objects.
The sub-classes (aka child classes) of Pizza are the implementations. These objects contain their specifc implementation of the common interface getPrice().
The factory method in this example is createPizza(PizzaType x). It isn't the getPrice() method.
In other words, PizzaFactory object has the factory method, not the Pizza objects.
I suggest that you purchase the Design Patterns book instead of relying upon the accuracy and content of "web pages." Keep in mind that the Abstract Factory and the Factory Method patterns are not the same. Make sure that the material you are studying does not mix up the definitions in error.
Hope this helps.