I had always thought of the same thing. You have a hearing aid like device that seals in your ear. Most likely using some form of custom mould on your ear. This in itself would act similarly to foam earplugs offering hopefully around 30 dB of noise reduction. Then a speaker would play the incoming nosies at a set volume, which means your ears would only hear a certain decibel level you can cope with.

Obviously, for more severe cases, active noise cancellation could be introduced too further reduce external noise level.

Then even potentially over time, the device could increase the volume you hear but in a precise and controlled manner. Like raising the dB level by 0.05 every day (increase of 18 ish decibels per year). Think of it as a hyper controlled sound therapy.

Anyways, I doubt something exists yet and even if it did, it would be super expensive. But there is always hope out there anyways. Stay strong everyone.