I setup an old phone just for that (https://news.ycombinator.com/item?id=37655746 https://news.ycombinator.com/item?id=37655746). It acts more as a backup key t

I setup an old phone just for that (https://news.ycombinator.com/item?id=37655746 https://news.ycombinator.com/item?id=37655746). It acts more as a backup key than as a backup smartphone. Just like with house/car/bike keys, having a spare in case of loss/theft can save you a lot of hassle.