From the docs :

cppyy is an automatic, run-time, Python-C++ bindings generator, for
calling C++ from Python and Python from C++.

(Emphasis mine)
I don't see any instructions for doing the same, however, so is it possible to call Python via C++ using cppyy?
I'm pretty sure cppyy only allows you to call C++ via Python, not vice versa. You could use Python.h, or use C++ to execute a python file as you would an .exe file, but that would require that the computer can run python files.
How to call Python from C++?