I wonder if at all it would ever be possible to get a section of the website which allows you to view a TV guide for all channels - I’m not sure how this would work for the US but I know there’s plenty of websites which pull UK EPG information.
On the page within the site and eventually the app, it would pull up the guide - allowing you to mark as watched. Obviously, we can’t sadly scrobble UK Virgin Tivo, Freeview boxes etc. That would be amazing but will never happen - so the next best thing would be an easy to choose from EPG.