>>> from gi.repository import Gtk. Gio
>>> Gtk.Application.do_startup == Gio.Application.do_startup
True

This shouldn't be the case. gtk_application_real_startup should be exposed as Gtk.Application.do_startup, because it's set in the class struct as the implementation of the vfunc. To do this properly,

gobject-introspection should tell us when a subtype puts a vfunc implementation in its class struct, so we can expose the function at that location. I don't know how much it would break if we just had a GIVFuncInfo* with the same name in the subclass's info.