Apnoea- absence if breathing is absolute. Snoring doesn't indicate sleep Apnoea, but it is worth observing whether your hinny stops breathing for a couple of seconds or more. Sleep studies are great - I've done one - minimal snore volume- despite the boss telling me otherwise - and no Apnoea. A good indicator is the level of tiredness despite long sleeps in him. Even without sleep Apnoea suggested can benefit from BiPAP/ CPAP machines which keep a pressure in the airways that can overcome snoring.

Losing weight is a major factor
Plenty of water- keeps the airways moist
Avoid dairy at night stops mucus thickening up.

Record him and play it back so he gets an idea of what it's like.

As for earplugs. Go for high attenuation ( noise suppressing quality) -26dB and up I think I bought my partner a big set but now I bought her a 10 dollar pair of non disposable Rock and Roll plugs which a great- from large musical instrument stores- there is a dearer pair at a higher attenuation too.

Be careful too though that aren't surprised with a recording that proves you snore too!!