I was replying to another post before it (rightfully) got deleted. Figured I’d write this as a separate one to help quell some of the mis-information floating around (so many people have suggested, with good intentions, that I need to eat more fruits/vegetables and do yoga to cure my sleep apnea — if only it were that easy).
Obstructive sleep apnea is caused by a physical _obstruction_. The things listed that actually help are the myofunctional therapy exercises you mentioned (which strengthens the muscles in your airways, preventing them from collapsing), and cutting alcohol (which relaxes your muscles, causing them to collapse even more) and tobacco.
Sidesleeping/positional apnea is also a thing, since sleeping on your back exposes your airways more to the effects of gravity, causing them to be more likely to collapse.
Cannabis might actually help sleep apnea by reducing REM cycles, the part of the sleep cycle where your muscles relax the most, causing apnea. So cannabis is helpful for reducing apneas, but only in a way that damages your sleep in other ways.
I’ve only heard of sleep apnea causing stress (since your body is stressed when it’s being deprived of oxygen, thinks you are dying repeatedly throughout the night, and so you’re not having continuous restful sleep — sleep deprivation is linked to increased stress) — never the other away around — so the causality there has not been established. Stress does affect sleep by causing insomnia — but not necessarily causing sleep apnea.
Vitamins, etc. are largely snake oil — I’ve only heard of anti-oxidants like NAC helping:https://pubmed.ncbi.nlm.nih.gov/21838198/
At any rate, you’re not going to have nearly the same kind of results you would actually treating your apnea with CPAP or surgery. If you think you have been cured (by CPAP or otherwise), the only way to know for sure is by getting another sleep study.