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I get the additional layer of backup, but remember you are riding 700km in Italy/France, not doing a month-long expedition into Tibet. Just saying, worst case you turn back down the hill and get back to the last house/village you rode by.
If you really want a map though, search for hiking maps of the most remote areas, have a look here: https://www.escursionista.it/categorie/cartografia/carta-escursionistica.html?mode=list#limit=25&mode=list®ioni_italia=7132
It's mostly in case my phone dies, gets lost etc I quite like to have a backup. I'd expect between the garmin track and the stuff on my phone I'd never need it but I'd rather have it and not need it than die, freezing 1km from a roaring fire :)