If exercise and diet worked well for OSA, we wouldn't have OSA. Exercise and diet don't work well because Americans aren't compliant.
Know what works great for Diabetes?
Know what works great for hypercholesterolemia/hyperlipidemia?
Know what works great for HTN?
Know what works great for H&N cancer? Not smoking and no oral sex. Well, neither of those is going away either.
Like it or not, options to treat all of the above are there for those who won't do the stupid simple things that fix all the problems to begin with.
CN XII stimulators are still in trial. I've referred 2 patients, both of whom have had pretty good (but not as good as CPAP) results (1 - AHI 48 to 16, 2 - AHI 54 to 21). They were friedman tongue position III and IV pt's with BMI <32 so not the typical fatty OSAers.