I think there is the risk of an increased reliance on devices with or without screen to be entertained and this at the cost of the child's imagination.
In early childhood there is this unique opportunity during the critical brain development. It is a moment for wonder and you can help build creativity , imagination in the same way you help him learn to talk and walk.
Throw a bedsheet on top of the dinning table and transform it in airplaine, a space craft, a submarine and visit country, galaxies or deep ocean . Take passengers on board, seatbelt on and so.
Take out all the fluffy toys and one day you play school, circus.... Pick up random object in the house and invent a game. Play doctor, play vet, all the profession.
Become a shop. One day it is a bookshop, groceries , create a cafe with a menu on a blackboard.
Slowly, one game after the other, he will make up his own games.
Reading a book and listening to a book don't develop the same level of comprehension.
You might get some time for yourself but the fact that it doesn't have a screen doesn't eliminate the fact that your child is surrounding his imagination and creativity to someone else's .
Instead on him listening to animal noises (which by the way is almost an insult at 4 years old), buy a big bag of animals and play farm, zoo, put animal by species, geographical area, kingdoms , play Noha's ark...
There is such a potential in a child's brain and wasting it on a device is just sad.