I really hope they let people playing split screen coop get the new achievements. Not everyone has an Xbox for their friend when they come to their house. Regardless, I hope the ability to play split screen coop doesn’t get taken out of the game.
You can only play split screen coop by using a workaround. There is no official support. IDK if it locks away achievements, IDK if it will not be patched out or if the method would keep working with future updates.