Just on AltUI:
The browser would be downloading any number of resources first time round from various servers. But I would have thought the majority of servers would be using some sort of cache control header combinations to the command the browser's caching. You don't need to be downloading jquery every time you hit a web page and I think it's unlikely that would be happening.
So I would have thought that the browser (for AltUI) could have cached most of what AltUI needed? What resource is the browser calling up that it can't download with the internet connection down? Maybe AltUI could have functioned but in some sort of reduced capability mode?
But yes the openLuup console, as I understand it, has been written to not rely overly on outside resources. Surprising akbooer could get it work!!