Babies physically have a small nasal passage, so often do make quite nasal sounds. It also means that if they get a cold, even a tiny amount of snot gives them a blocked nose.
There is nothing inherently wrong with baby making nasal noises, assuming he is well. It will just be general baby noises. No need to medicate him unless you feel he is struggling in some way.
There's something FTM about being disturbed by these snuffly noises. By the time you've had two, three, four... children you just sleep through it.
A dummy may help quieten him down.
If you notice other symptoms, if he is sick more than normal, foamy poo, chest pulling inwards quite deeply, temperature, skin colour change - go to the doctors straight away.
If the only symptom is noisy baby at night, that's just baby being a baby I'm afraid.try a dummy.