Flat surface cracker here (I use a plate). Once you have a crack, pull the two halves apart. I’ve seen professional cooks who can do this pull with one hand. When I asked one about his technique he told me I should practice the one-handed pull apart with two golf balls in one hand. I never mastered it. But two-handed, I almost never get egg shell shards. And, if I do, I’ve discovered that the easiest way to grab that bit without chasing it all over was to wet my hand first.