---

import sys
from PyQt6 import QtWidgets
from PyQt6.QtWidgets import *

app = QApplication(sys.argv)

stack = QStackedLayout()

page1 = QLabel("Страница 1")
page2 = QLabel("Страница 2")

stack.addWidget(page1)
stack.addWidget(page2)

btn1 = QPushButton("<-")
btn2 = QPushButton("->")

def go_to_page1():
    stack.setCurrentIndex(0)

def go_to_page2():
    stack.setCurrentIndex(1)

btn1.clicked.connect(go_to_page1)
btn2.clicked.connect(go_to_page2)

layout = QVBoxLayout()
layout.addLayout(stack)

btn_layout = QHBoxLayout()
btn_layout.addWidget(btn1)
btn_layout.addWidget(btn2)
layout.addLayout(btn_layout)


window = QWidget()
window.resize(300, 600)
window.setLayout(layout)
window.setWindowTitle("Две страницы")
window.show()
sys.exit(app.exec())