We were able to minimize motion sickness by having using a 3d "nose" and food tray as stationary objects to ground the player. We also used as much flat, undetailed textures as possible and added vignettes to lower FOV.
The player controls the plane by looking in the direction they want to fly in, but in early tests, we found that players were unable to notice this was happening. To make the player aware, we added floating cloud particles that flew by for the player to have a point of reference for their direction.
The level opens facing the mother, and her placement in the level allows the player to understand the level's direction. Looking behind you shows a dog eating all the food you dodge!