The switch version didn't come into being until last Spring according to this interview with the director
The big Zelda: Breath of the Wild interview The interviewer is stuck on this being in the timeline of Wind Waker, which Eiji shrugged off. There was going to be more interaction with the Wii-U gamepad but it looks like they took it away to make it equal to the Switch version.
Cliff Notes:
We pictured the Sheikah Slate as reminiscent of a Wii U GamePad. I think the Sheikah Slate's size and appearance resembles a Nintendo Switch too.
Loading times on Switch are slightly faster. That stems from the media that the game is on - Wii U loads from a disc, Switch is on a Game Card.
One of the major problems we faced was making sure all the development staff played the game as much as possible to make sure that cohesion was maintained.
A challenge we faced was the physics engine. One day I picked up the latest build and saw that all the objects that were supposed to be in that area weren't there. I was quite surprised and confused, and I realized after asking the programmer, the reason the objects weren't there was because the wind in-game had blown them all away.