.pyproject file is an ad-hoc file that was created only for QtCreator to recognize python projects. Before that the file was called '.pyqtc' from 'python' and 'qt creator' but people thought 'pyqtc' was "PyQt Creator". It's just a simple file that instead of having a "one file per-line" it it's a json file that has the only field "files" that needs a list of strings for the files in your project.