The jig is up.
I’m not sure if it was entirely accurate for the PythonCall developer to say that JuliaCall is just “one [Python] file” (pysrc/juliacall) that has to “find Julia and get it to import PythonCall”; the Julia code (src/jlwrap) that wraps Julia types for Python does execute strings of Python code interpolated with computed Julia literals. But that just goes to show that it’s a vastly different approach to PyJulia, which is basically a Python package.
I’ll draw your attention to this comment by one of the developers of PyCall; I have not seen a similar comment from a PyJulia developer. TLDR: PyCall and PyJulia were created in Julia’s volatile package-lacking v0 phase, and a reasonable design overhaul for the different needs of today would be such a disruptive major revision, it warrants a different package.