hello and welcome to HCM,
As you rightly pointed out there are few definitive treatment strategies for tinnitus
but we are learning more and more everyday.
Coming to your case in point, Deviated nasal septum
can be a cause for tinnitus especially if it is only one one side but there is no absolute way to confirm that this is the definitive cause. The same with eustachian tube block. Unless of course you go for a surgery and the tinnitus gets relieved!
But surgery for deviated nasal septum is indicated only for other conditions such as nose block and nose bleed. So if you do opt for the surgery do so only if you have these symptoms and if your tinnitus does stop then its an added bonus.
I have had sufficient amount of control of essential tinnitus of late with the use of a prostagladin analogue which comes both as a tablet and injection. Ask your ENT for the same
all the best
Dr Sriram Nathan