It seems like it would be easier and more performant (begin heresy and likely vast oversimplification) for PyPy to have a mostly complete implementation of CPyt

It seems like it would be easier and more performant (begin heresy and likely vast oversimplification) for PyPy to have a mostly complete implementation of CPython that it interacts with at the object level such that each object in PyPy could be a PyPy GC object descended from W_root or a CPython RefCount object implemented on PyObject*. There would be many points where you would still have to convert to make operations work. Either way, running under the assumption of "objects from CPython or objects that are passed to CPython are more likely to interact with other CPython objects, so lets not convert them back until we have to" might result in closer to CPython performance for code with a lot of CPython extensions. Does this seem reasonable? Is this even possible? I don't know much about the internals of PyPy...