To unlock the Hunger trophy in Little Nightmares 2, you’ll need to pull on a vending machine's handle five times on the Hospital level/chapter three. Although this trophy is straightforward, it can easily be missed. Thankfully, you can still unlock the achievement using the game’s chapter select if you didn't grab it initially.
The vending machine can be found shortly after picking up the flashlight and after walking through the darkened corridors. You will need to pull on the vending machine's handle to grab a can to throw at the button and unlock a door across the room. Once you have one can, jump and pull on the handle five more times until cans stop being dispensed. The trophy will pop shortly after the final can rolls out.