Have him talk to his doctor about it as it could be sleep apnea. I'm awaiting results from a sleep study for my own issues (it's taken a long time to get it done), but because I have complained about my sinuses closing up at night, we got these: https://www.amazon.com/Anti-Snoring-Nose-Vents-Breathing/dp/B07D38TJ61/ref=sr_1_13?dchild=1&keywords=snore+stopper+nose+vents&qid=1627429004&sr=8-13
My husband says I haven't snored since we got them. They are fairly comfortable, once you get the right size. Maybe those would help in the mean time?