Two questions...
Does the VivoActive 3 need a screen protector?
And if so, what's a comparable size? Not seeing any listed for the VA3 but is any of the other Garmin watches the same size?
Corning's Gorilla glass is scratch resistant and not scratch proof. My cell has Gorilla glass and has been dropped from 25 feet plus several times (I work in a tower truck) without cracking, but I have several scratches on it. If you think you may be in a situation where you may scratch your watch face, I suggest getting a protective cover. A tempered glass cover is easily replaced, where a scratched watch face is permanent.