I’ve used a CPAP machine with nasal pillow mask for around 15 years now. Wouldn’t lay down without it now. Like some others have said in the comments, I have chronic sinus issues which used to inhibit sleep - the CPAP helps keep the airways clear. I used to use Flonase at night along with a nightly nasal rinse (aka nose douche) - but I had sinus surgery earlier in the year and the doc prescribed Budesonide to mix with the salt in the nasal rinse. This delivers steroid up into the sinuses better than Flonase and it has been a big help.
Did you ever try EPAP?