Ahh! One of the joys of being an old-timer with a first generation iPad Mini: no updates available beyond 9.3.5!
My iPad Mini is my Marvin3 eReader, email reader (not email writer), and "Googler". It meets those needs 100%. For the heavy-duty stuff, I prefer using my desktop with a real keyboard, mouse and 21-inch monitor.
I've already warned my wife that her iPhone will start another round of pestering her to update.