I want to have a few pages at the bottom of navigation pane but I can not find in code where the Settings navigation is added. Do you have any advice?
There is a documentation for NavigationView
https://learn.microsoft.com/pl-pl/windows/apps/design/controls/navigationview
Look for "Footer menu items"
You can add Footer menu items.
<NavigationView>
<NavigationView.MenuItems>
<NavigationViewItem Content="Menu item 1" />
<NavigationViewItem Content="Menu item 2" />
</NavigationView.MenuItems>
<NavigationView.FooterMenuItems>
<NavigationViewItem Content="Footer menu item 1" />
<NavigationViewItem Content="Footer menu item 2" />
</NavigationView.FooterMenuItems>
</NavigationView>
By the way, you can also add items to Pane footer but they are not included in the selection process, so you can click them but they won't change the selection.