Has there never been found physical artifacts on any of the possible routes?
Nothin’. Of course, these routes were heavily in use ever since that time, and anything left setting around (for example, by someone who’d died) would have been grabbed by either a survivor of Hannibal’s army, or by passersby during the following years. Trade went on after the army went over. His crossing of the Rhone was also stupendous — rafts were built and covered with turf so the elephants would go aboard, then they were launched, then poled and paddled across. The Gauls waiting on the opposite bank didn’t like the look of this, and amscrayed.