Enlarging the jaw is still very much under the scope of orthodontics. Palate expanders are fairly common, and are used to expand the adolescent jaw. I had one as a kid. It absolutely works. Their are devices for lower jaw expansion as well.
The pseudoscience-y orthotropics part is where adults are told they can expand their fully developed jaws.
I had a palate expander in my youth. It did not change the forces I applied to my jaw, so it didn't solve my problem, instead they emerged and re-emerged, first in my teens, then after I stopped wearing a retainer in my 20s.
What's the basis for your eager dismissal of an alternative?
The pseudoscience-y orthotropics part is where adults are told they can expand their fully developed jaws.