I'm in my early 30s, and I recently had my maxilla and mandible non-surgically expanded with a combination of appliances, one called Advanced Lightwire Functional (ALF) and the other called Fixed Anterior Growth Guidance Appliance (FAGGA).
Treatments that make use of the Orthotropics philosophy or of appliances like the ALF or FAGGA are relatively new and are not mainstream. However, there are many case studies available online showing them in action and showing before/after pictures.
I don't know what kind of resources you're looking for, but this video [1] provides a quick introduction to Orthotropics.
From the what I understand, the FAGGA basically expands your maxilla forward. Here's a good example [1] that shows the appliance in action. The photos showing the upper jaw after FAGGA insertion match my experience.
The ALF can be applied to both the maxilla and mandible (whereas the FAGGA, I believe, is just for the maxilla), but the growth it promotes is more gradual and subtle.
I don't think either appliance shares much in common with lingual braces, functionally speaking. I'm not a doctor, but from what I understand lingual braces act primarily on the individual teeth whereas the ALF and FAGGA act primarily on the jaw bones.
Treatments that make use of the Orthotropics philosophy or of appliances like the ALF or FAGGA are relatively new and are not mainstream. However, there are many case studies available online showing them in action and showing before/after pictures.
I don't know what kind of resources you're looking for, but this video [1] provides a quick introduction to Orthotropics.
[1]: https://www.youtube.com/watch?v=_D70VF43Evw