You likely want to use something like https://github.com/jupyter/jupyter_console, or ipykernel directly to have a persistent python process. One issue is that shells are text based, so you have to do a lot of serialisation/deserialisation.

But honestly at that point I would just look into https://xon.sh/ that blends Python and Shell together. IPython and Xonsh devs are friends, so if you need anything from one into the other it's likely doable.