Dynamically linking a pip native package to another pip package

Question

I am building a python module using C++ with pybind11. This project will depend on two separate packages, that provide bindings for native C++ libraries:

• opencv (provided by the pip package opencv-python)
• imgui (provided by the pip package pyimgui).

This packages, once installed, consist mainly of dynamic libraries, plus some glue code in python.

My question concerns the installation/build process on the final user computer, i.e when pip install . is launched (in build isolation mode): how to find the path to the third parties dynamic libraries when linking?

In the end, they will be located somewhere in the virtual environment of the user; but I need to link them during the pip build (in isolation mode), and I also need to ensure that they will be found when the module will be used.

Note: as far a opencv is concerned, I could link to a local installation of OpenCV (i.e require the user to apt install opencv before, and use find_package(OpenCV)), but I suspect this is not the way to go. Concerning imgui, this solution would not apply.