Fire and forget a QThread that updates a QLabel in the main window with pyside6.

import sys
import time
from PySide6.QtWidgets import QWidget
from PySide6.QtWidgets import QMainWindow
from PySide6.QtWidgets import QApplication
from PySide6.QtWidgets import QLabel
from PySide6.QtWidgets import QVBoxLayout
from PySide6.QtCore import QThread
from __feature__ import snake_case, true_property

class FireAndForget(QThread):
def __init__(self, max, sleep, label):
super().__init__()
self.label = label
self.max = max
self.sleep = sleep

def run(self):
for x in range(self.max):
    self.label.text = f"Count {x}"
    time.sleep(self.sleep)  # or use self.msleep(ms) as alternative

class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
centralwidget = QWidget()
self.set_central_widget(centralwidget)
verticalbox = QVBoxLayout(centralwidget)
label1 = QLabel()
label2 = QLabel()
verticalbox.add_widget(label1)
verticalbox.add_widget(label2)
self.set_layout(verticalbox)

self.t = FireAndForget(7, 1, label1)
self.t2 = FireAndForget(50, .15, label2)
self.t.start()
self.t2.start()

app = QApplication(sys.argv)

mainwindow = MainWindow()
mainwindow.show()

app.exec_()