Despite its advanced age, the Gorilla Glass 3 technology used to protect the affordable handset’s 60Hz 6.1-inch OLED screen offers solid scratch resistance by any and all modern standards. Because there’s no such thing as unbreakable glass, putting on a case is a good idea no matter what phone you own and how much you’re willing to spend for a new model.
That being said, you should probably not worry about keys or coins causing much damage to an “unprotected” Pixel 6a, which combines a strong metal frame with a shiny glass front and an almost surprisingly good-looking plastic back that also feels very nice and sturdy in the hand.