Very good. I'm pretty sure this is the softest chicken I've ever eaten. I don't know how they do it.
They probably "velvet" the chicken first. Coat it, marinade, cook just 1-2 minutes in boiling water. Then prepare the usual way. For example:
https://www.instructables.com/How-to-Velvet-Chicken/Two possible explanations for why it works:
Boiling causes the coating to adhere to the chicken surfaces, creating a seal that keeps more of the moisture inside, so it stays soft.
The heat and/or marinade breaks up the tough protein that holds the muscle bundles together (kinda like long cooking of cholent breaks a solid chunk of raw flanken into "stringy" meat.