There's no way you can cut your wrists on the edge of a MacBook. To do that, you would have to be leaning straight-armed with all of your weight on the edge of the keyboard, which is a typing style that I've never seen. Mac keyboards are some of the best that I've ever used. There's nothing special about the Mac screen one way or the other.
You sound very confident. My M1 mbp’s edges are uncomfortable enough against my wrist/heel (?) area that I use an external keyboard even when on the couch.
Could it slice me open? Probably not without effort. Is it sharp, and sharp enough to cause discomfort? Definitely.