How to set PYTHONPATH for python shell based on project root?

[orlandini]

Hello,
I am using pyright and I am currently able to detect my (sub)project root by means of a .projectile file in the desired directory.
In this way, pyright finds all my modules as expected.

Now, I would like to start a python shell with the project root directory prepended to my existing PYTHONPATH.

I've found a way to change the working directory of the python interpreter:

(defun my-run-python ()
  (interactive)
  (let ((default-directory (or (projectile-project-root) default-directory)))
    (call-interactively #'run-python)))

However, this is not the behaviour I intended. I just would like to prepend (projectile-project-root) to the PYTHONPATH seen by the python interpreter when called through run-python whenever I am in a project using pyright. Perhaps using lsp-pyright-extra-paths would be useful, but I am not an expert in Lisp.

Best regards and thank you in advance,

Francisco