Add whole chicken to pot, breast side up. Then add aromatics and seasonings – onion, thyme, garlic, bay leaf, salt, and pepper. Then add 6 cups of water. Lock lid and cook for 35 minutes at high pressure.
Meanwhile... chop all your other veggies.
Once cook time is complete, allow pressure to release naturally for 30 minutes. If there is any pressure left, go ahead and do a quick-release.
Remove chicken and transfer to a large bowl. It should be falling apart (which is a good thing!), so you may need to do this a little at a time. Using some sort of strainer, remove all remaining aromatics and chicken remnants from the broth.
Add diced onions, celery, carrots, lemon juice, and noodles to broth. Lock lid and cook for 2 minutes at high pressure.
Meanwhile... remove all meat from chicken and shred into bite-size pieces. Discard skin and bones.
Once cook time is complete, you’ll need to do a controlled quick-release (meaning only open vent halfway, and open for a few seconds at a time). This type of noodle will cause starchy bubbles that may try to escape through the steam vent if you release too quickly.
Return meat to pot and give a good mix. Serve hot!