I’ve seen some old Android based eReaders that people still use, but never got updated beyond Android 4.4. Heck, I used a rooted Nook Simple Touch for years, and that thing was running Android 2.1. I only upgraded when the battery was dying out and most software was dropping support for it, since I was using it to read books and news articles, not to do banking.
I’ve also seen some older folk that still rock Android 4.x devices. They didn’t want to upgrade because they had their phones for so long they missed the incremental Android UI changes and were now confused by newer phones. I had to force a couple relatives to switch to new phones since the networks were shutting down 3G support.