Aqui um exemplo básico:
#!/usr/bin/env python
from gi.repository import Gtk, Vte
from gi.repository import GLib
import os
terminal = Vte.Terminal()
terminal.spawn_sync(
Vte.PtyFlags.DEFAULT,
os.environ['HOME'],
["/bin/sh"],
[],
GLib.SpawnFlags.DO_NOT_REAP_CHILD,
None,
None,
)
win = Gtk.Window()
win.connect('delete-event', Gtk.main_quit)
win.add(terminal)
win.show_all()
Gtk.main()