The primary obstruction in sleep apnea is typically at the back of the airway, not in the nose, and is often exacerbated by gravity or mouth opening.

“how do you go about differentiating if it's like caused by allergies or positional or you know something something like nasal congestion?”

“remember the obstructions almost all the time are back here in that 90° angle in your airway. It's not up here. It's like people think snoring is is a nose-based thing. It really isn't. Sometimes you get like sort of floppy nostrils or whatever, but almost entirely it's that the issue is back here. It's the back of your tongue. That's also why on your back it's worse often because gravity starts pulling stuff back or like when you open your mouth and your tongue falls back and can block the airway.”