The easiest way I can see to do this is to have your computer set up to auto-login ( eg maybe something along the lines of
https://askubuntu.com/questions/175248/how-to-autologin-without-entering-username-and-passwordin-text-mode ) ... and then have it start X automatically ... but with a ~/.xinitrc that launches *just* your python app, instead of a window manager. Then if the user has done what's needed, you'd have your app launch a window manager. I'd do it like this because once a window manager is running, you don't have a reliable way of preventing users from escaping your app. Maybe there is a better way?
