Feature

code objects do not have the following attributes

• co_varnames: typing.Tuple[str, ...] (see this issue, Add json output for CPython tests #1834)
• co_names: typing.Tuple[str, ...] Add co_names to PyCode #4177
• co_cellvars: typing.Tuple[str, ...] Add co_cellvars to code object #4507
• co_freevars: typing.Tuple[str, ...] Add co_freevars to code object #4509
• co_nlocals: int (=len(self.co_varnames)?) Add co_nlocals to code object #4553
• co_stacksize: int Add co_stacksize to code objects #4554
• co_code: bytes (only useful if the bytecode is cpython compatible)
• co_lnotab: bytes (line number <-> byte code index)

Maybe it does not make sense to implement the last two or three items (as far as I know the bytecode is not cpython compatible?). But the other ones can be implemented, I think.
I wish I'd be able to do that, but the only language I really speak is python 😞.

Example

# cpython 3.8
import inspect
from pprint import pprint

def code_info(code): 
    return {(k1:=f'co_{k}'): getattr(code, k1) for k in ('names', 'varnames', 'cellvars', 'freevars')}

def foo(arg1, arg2=None): 
    x_foo = 42 
    def bar(arg_bar): 
        x_bar = 73 
        return arg_bar * x_bar, x_foo, arg2 
    return bar, inspect.currentframe()

bar_func, f = foo(1)
pprint(code_info(f.f_code))
pprint(code_info(bar_func.__code__))

should print

{'co_names': ('inspect', 'currentframe'),
 'co_varnames': ('arg1', 'arg2', 'bar'),
 'co_cellvars': ('arg2', 'x_foo'),
 'co_freevars': ()}
{'co_names': (),
 'co_varnames': ('arg_bar', 'x_bar'),
 'co_cellvars': (),
 'co_freevars': ('arg2', 'x_foo')}

Note that with #1834 f.f_code.co_varnames is ('arg1', 'arg2') (bar missing) and bar_func.__code__.co_varnames is ('arg_bar',) (x_bar missing).

Python Documentation

cpython source code