Three more things to try if you haven’t, on a “can’t hurt” basis: nightly Avamys spray (might need a scrip depending on where you are), magnesium glycinate before bed, little bits of plastic that go inside the nostril and hold them open.
Also worth a try... B1 (thiamine) seems to help for me. I don't have objective numbers, but I disturb my spouse with my snoring and breathing troubles far less. I believe I have (undiagnosed) central sleep apnea rathee than OSA though, it's been a long time since I had a sleep study, but I had only one event over a few recorded nights... But some nights it's pretty bad.
I just discovered magnesium glycinate provides significant relief for my night sweats. I might have some undiagnosed apnea, but the sweats have been the only apparent symptom (and may be caused by a completely unrelated problem). Taking 400mg before bed seems to have turned off the symptom like a switch. YMMV, of course.
Annoyingly, this symptom had been discussed with numerous doctors for over a decade. I got zero constructive advice from the medical establishment. In most cases, they even showed disinterest and moved on as quickly as possible. Beyond worthless.
On a lark, I fed an AI a two sentence prompt and one follow-up question, and it was able to piece together data and give me the suggestion with solid reasoning behind why it might work. In less than 30 seconds.