Ensure you have created and opened your project as a python project. (It should have a .pyproject file).

Then it is straightforward: create a new run configuration and run/debug it.

Notes:

• You might want to enable only the python debugger, not the C++/QML ones
• You don't need your app to be a pyqt app, nor need pyside6
• Tested on Debian unstable, amd64, with python 3.13 and qtcreator 15.0.0