CBT-I is not a cure for insomnia, it's sleep hygiene by a better name. There is no reason to pay a huge monthly fee for a CBT-I app. Sorry OP. This is something anybody can do themselves with a bit of research. If you are going to a "sleep therapist" it is also probably 70% of what you will hear, the other 30% likely will be how maybe you have apnea. I'm so saddened that this is the state of sleep science (which is why I started my start-up - more below).
I'm not saying sleep hygiene isn't good, it is important, just like brushing your teeth and not eating too much sugar. But those are the basics for a healthy lifestyle, not some genius treatment for an illness.
Sleep restriction therapy is a different beast all together. It is actively harmful to restrict your sleep. The damage is not worth the benefit. And yes, we are very aware that lack of sleep is damaging, so why do we recommend people do this?
I did find it interesting that you bought an EEG device, and curious if you learned anything from it, aside from how difficult it can be to sleep with a "research grade EEG device".
I'm in the neurotech/sleeptech space as the co-founder of https://soundmind.co - we are NOT in the insomnia space, we focus on improving the neurological function of your brain during sleep.