I using arch linux - monjaro
Operating System: Manjaro Linux
KDE Plasma Version: 5.22.3
KDE Frameworks Version: 5.84.0
Qt Version: 5.15.2
Kernel Version: 5.10.49-1-MANJARO (64-bit)
and I can't find "Pyside2" module, I searched in user dir, in root, I find just python2.7 with one dir "site-packages" and python3.9 without lib dir, then when I opened site-packages I found others modules but not my, and yes I installed it from pip
pip install PySide2
Install build dependencies:
$ sudo apt-get install build-essential git cmake libqt4-dev libphonon-dev python2.7-dev libxml2-dev libxslt1-dev qtmobility-dev libqtwebkit-dev
Install latest pip distribution into the Python you installed in the first step:
download get-pip.py and run it using the python interpreter of your Python 2.7 installation using a command prompt:
$ wget https://bootstrap.pypa.io/get-pip.py
$ sudo python2.7 get-pip.py
Install latest wheel distribution:
$ sudo pip2.7 install wheel
Building PySide distribution Download PySide source distribution:
$ wget https://pypi.python.org/packages/source/P/PySide/PySide-1.2.4.tar.gz
Extract the source distribution:
$ tar -xvzf PySide-1.2.4.tar.gz
Switch to the distribution directory:
$ cd PySide-1.2.4
Build the wheel binary distribution:
$ python2.7 setup.py bdist_wheel --qmake=/usr/bin/qmake-qt4
Optionally you can build standalone version of distribution with embedded Qt libs:
$ python2.7 setup.py bdist_wheel --qmake=/usr/bin/qmake-qt4 --standalone
https://pyside.readthedocs.io/en/latest/building/linux.html
Ok, if that doesn't work, try the snap store.