When having more items in the drawer content, the content does not resize dynamically, so the items to be visible. There is an inconsistency on the platforms:

On WinUI the drawer content does not display at all

On Android, the content displays as expected

On iOS and on MacCatalyst, the drawer content does not measure as expected. part of the content is not displayed. 

The workaround for now is applying a fixed length by setting the SideDrawer.DrawerLength property.