This is a solid first game! I beat it, and it was a nice classic maze experience. Having the player carry something around is trickier than it sounds, and I think you did a good job tackling that.
However, if I look down while holding the box, I can fly upwards out of bounds! Also, the text on the screen is reaallyy tiny on my screen, so make sure your Canvas component in Unity is set to "Scale With Screen Size".