Update QGIS window title with Python

Minimal Examples

A minimal example for a script that edits the title bar of the QGIS app window on application launch by adding a QGIS version number to it.

C:\Users\Agnieszka\AppData\Roaming\QGIS\QGIS3\startup.py:

from qgis.utils import iface
from qgis.core import QgsExpressionContextUtils
from qgis.core import QgsProject

def customize():
    version = QgsExpressionContextUtils.globalScope().variable('qgis_version')
    title = QgsProject.instance().title()
    if title.strip() == "":
        title = f"Untitled | QGIS v.{version.split('-')[0]}"
    else:
        title = f"{title} | QGIS v.{version.split('-')[0]}"
    iface.mainWindow().setWindowTitle(title)

iface.initializationCompleted.connect(customize)
iface.projectRead.connect(customize)
iface.newProjectCreated.connect(customize)

This script was based on PyQGIS Masterclass - Customizing QGIS with Python course chapter 7. Running Python Code at QGIS Launch.