Py_CompileString and PyParser_SimpleParseString and possibly other related functions are not exported in Python 3.8 b2 DLL. This is unintentional, not documented and unnecessarily breaks backward compatibility.
Issue 37189 was similar and related to PyRun_String. This was fixed in Python 3.8b2. Please provide fixes to the above two functions as well.
To confirm the error:
>>> import ctypes
>>> api = ctypes.pythonapi
>>> hasattr(api, "PyParser_SimpleParseString")
False
>>> hasattr(api2, "Py_CompileString")
False