The identity of this child is unknown to us as of now, but it could be Nick or Rick, the son of Steve and Peggy Carter, from a few scattered stories from Marvel comics.

In terms of Doomsday’s plot, with Rogers’ teaser focused on his baby, Thor’s on his missing daughter and our first look at Doom was him with Franklin Richards, it would seem possible “Doom steals all the superhero kids” could be an impetus for the story here.