Python subprocess fails to execute Pip-installed module

[Pradana Adrinusa AUMARS]

I need to use Ray (https://www.ray.io) for a project. Because Guix does
not have a python-ray package, and I don't really have time to package
one myself, I installed Ray using Pip (user installation is the
default, since system installation isn't possible on Guix).

Running:

import ray
ray.init()

fails since Python's subprocess needs to run an executable located in

~/.local/lib/python3.9/site-packages/ray/core/src/ray/gcs/gcs_server

So the error is narrowed down to:

import subprocess
subprocess.Popen(["/home/user/.local/lib/python3.9/site-packages/ray/core/src/ray/gcs/gcs_server"])

It doesn't seem to be a $PATH issue. $PATH does not have ~/.local/bin
and

import subprocess
subprocess.Popen(["/home/user/.local/bin/any_binary"])

works normally.

I've also tried adding 
/home/user/.local/lib/python3.9/site-packages/ray/core/src/ray/gcs
to $PATH, and it doesn't work.

I could package Ray, which would be the permenant solution, but I'm
limited on time right now. Does anyone have a temporary solution to fix
this issue?

Thanks.