Problem running a PyQt5 project in WSLg - no application window shows up - pyqt5

Question

I am running WSL2 under Windows 10.
If I type "gedit &" into the WSL console, the Gedit application window pops up. Thus I assume that WSLg properly works.
Next, I am trying to run the following PyQt5 project:
https://github.com/rafaelpadilla/review_object_detection_metrics
However, no application window pops up this time, although no error message appears either.
First of all, I do wonder whether this could work at all with WSL!?
Appendix for additional context:
I am not using conda because of licensing issues, but a combination of pyenv + poetry instead. First I had problems with a missing library (libxcb.so), which I could solve by running "sudo apt python-pyqt5". Now everything seems to work, except from no application window being shown.
UPDATE:
I tried with "/src/pyqt-official/qtdemo/qtdemo.py" from the official PyQt Examples github repository and I observed exactly the same issue.
There is no error message. Last prompt informs me that the "xcb plugin was loaded“, then nothing happens. In particular, no window is showing up.
Some related observations:
(1) I haven't yet updated my grafics card driver to support vGPUs. However, Gedit works and opens in a separate window.
(2) Unless I do "sudo apt install python3-pyqt", I receive an error message saying that it cannot find "libxcb.so". However, I am running the code in a virtual pyenv/poetry environment, which is separate from the system python installation. I don't understand why "sudo apt install python3-pyqt" makes a difference here. Shouldn't installing "PyQt5" with poetry obtain a wheel that comes with all libraries already compiled? I don't understand how all of this is playing together.
Open Questions:
Do you think the driver issue could be an explanation? I actually cannot imagine that. I thought it is only about better performance for OpenGL applications.
Can you explain observation (2)?
What else can I do?

Answer 1

First of all, I do wonder whether this could work at all with WSL!?
I can't tell you if that particular application will run under WSL, but my expectation is that it will. As far as I can tell in its dependencies there doesn't seem to be any reliance on GPU compute. That, to me, would be the trickiest part to configure under WSL (but is still typically possible). However, there may be other dependencies (not covered below) that you need to get running before the application can work.
What I can confirm is that PyQt works under WSL just fine. However, keep in mind that a default Ubuntu installation under WSL is based on a non-GUI Ubuntu Server distribution, rather than standard Ubuntu (with a desktop and GUI).
This means that Ubuntu Server is often missing system level libraries needed for GUI support, which appears to be the case here.
I don't understand why "sudo apt install python3-pyqt" makes a difference here. Shouldn't installing "PyQt5" with poetry obtain a wheel that comes with all libraries already compiled?
Poetry and/or Pip manage the Python library dependencies, but those Python libraries still require the native system library dependencies. That's where sudo apt install python3-pyqt5 comes in. Under a desktop Ubuntu system, most of these libraries would already be in place. However, with Ubuntu Server/WSL, they aren't.
For reference, here's my configuration. On a freshly initialized Ubuntu 22.04 WSL2 distribution:
sudo apt update && sudo apt upgrade -y
sudo apt install python3-venv python3-pyqt5
mkdir -p src/pyqt_test
cd src/pyqt_test
python3 -m venv .venv
source .venv/bin/activate
pip install pyqt5
I was then able to create and run the following, taken from Learn Python PyQt:
import sys
from PyQt5 import QtWidgets
app = QtWidgets.QApplication(sys.argv)
windows = QtWidgets.QWidget()
windows.resize(500,500)
windows.move(100,100)
windows.show()
sys.exit(app.exec_())
The window displayed correctly.