But at what point do function calls from ceval.c stop counting as part of the interpreter? Okay, calling a C function clearly at some point ceases being part of

But at what point do function calls from ceval.c stop counting as part of the interpreter? Okay, calling a C function clearly at some point ceases being part of the interpreter, but is the entirety of an attribute lookup (i.e., executing the LOAD_ATTR inst) on an ordinary Python object part of the interpreter or the runtime? In plenty of VMs the object representation is an intrinsic part of the VM design, with the VM having deep knowledge of it.