I would say intrusive (to the ability to sleep), rather than invasive.

I tried CPAP. I am a frequent tosser-turner and the pull from the hose was enough to awaken me dozens of times per night, which obviously defeats (part of) the purpose.

My mouthpiece (custom fitted and gradually adjusted with progressively tighter bands by the doctor) doesn't have that problem. It isn't quite as effective as CPAP per the sleep studies, but together with side sleeping it's close.