Shared Nursery Boy/Girl

Son will be 19-20 months old when Baby Girl gets here and I need help 😭 right now our nursery is all Construction, Trucks and Cars. I have a plan of HOW to split up the room, but I dont really wanna take all of my son's decor and redecorate to something more gender neutral when he's had it up since he was a newborn...idk maybe it's just me overthinking lol. How did you go about room splitting?