https://www.affectablesleep.com/how-it-works
Bottom of the page.
Don't think of it as "sound", this isn't "gentle tones to help you sleep", and it isn't played during a particular "phase" of sleep.
It is specifically targeting individual slow-waves.
Think of it more like applying an electrical stimulation to a muscle while lifting weights, not just pumping heavy music into the gym.
Closed-loop neurostimulation, not neuromodulation.
However, you are 100% correct that overcoming the snake-oil factor is a significant challenge for us.