> BTW how else are methods/functions are created in Python except via def?

Functions are objects like everything else in Python, so they have a 
type, which has a constructor:

    from types import FunctionType

The documentation for FunctionType is a bit thin, so you may need to 
experiment a bit to get the details right, but it can be done.

Unfortunately copy.copy doesn't actually copy functions, which is in my 
opinion a bug (see #39805) but if you search the internet, you will find 
code that makes independent copies of function objects.

Methods are different from functions, and like functions, they 
too have a type with a constructor:

    from types import MethodType