not a dentist i have a deep bite also if you try to correct it yourself you will hurt yourself very badly DO NOT TRUST TIKTOK also you need an orthodontist specifically
If your insurance doesn't cover *orthodontics you can try a sleep specialist maybe they can give you guidance on things like sleeping position to reduce sleep apnea.
your other options are seeing if there's a nearby dental school you can be practiced on by students for cheaper. Or going to Mexico.