I've google images of Green peachicks at at hatch out of curiosity because this egg had a "G" label. I can't tell but regardless it looks big to me.
I definitely don't think it's normal.
I don't know anything about peas so maybe I shouldn't even comment but my purebred silkies hatch like that and alot die in the shell because they have been bred to have a vaulted skull. And they look just like that! Do any pea breeds have vaulted skulls? Is the bp hard or soft to touch?