Place all ingredients into the Instant Pot.
Place the lid onto the pot, make sure the lid is sealed and the dial is not pointing towards vent.
Press the 'Poultry' button followed by the 'Adjust' button to light up the high-pressure light.
Adjust the time using the '+' button to read 25 minutes.
The Instant Pot will automatically pre-heat (about 15 minutes depending on your Instant Pot) and start the time once ready.
When the 25 minute cooking time is complete, carefully vent the Instant Pot.
Caution, the steam is very hot!
Once all steam is released open the lid and shred the chicken.
Keep shredded chicken in the pot and stir into the now cooked onions and spices. Keep warm.
In a small bowl, place the cucumber and sprinkle the salt on top. Set aside for at least 5 minutes.
Meanwhile, combine remaining ingredients and mix well.
Once the cucumber has rested, squeeze out any excess liquid and add to the yogurt mixture, mixing well to incorporate the cucumber throughout the yogurt.
Place about 1/4 cup of the chicken and 1 or 2 tablespoons of the Gyro sauce on top of a pita.
Top with tomato, red onion, lettuce, and feta.
Serve and enjoy!