To do that, they’d need to measure the sound pretty close to the eardrum or at least in the ear canal. There’s nothing that does that yet. Modern noise cancelling headsets still rely pretty heavily on closing off the ear.
I agree with Neville’s take. I sure wish highly effective passive and active noise reduction helmets were available when I was flying military helicopters in the 70s 
Looking at headsets for helicopter pilots, most rely on significant passive noise reduction. One relatively expensive model (US price of about $900) for which there are actual specifications (that I could find) on the active noise reduction stated that the active reduction was effective only between 20 Hz and 1 KHz and that the frequency for peak reduction was at 150 Hz.
Effective active noise reduction relies on supplying an additional signal of nearly the same sound pressure level and frequency as the noise source at the point where the sound is to be cancelled. For most people, that would be at the eardrum so the added signal and the noise would be 180 degrees out of phase and of equal amplitude to get full cancellation. Passively reducing the noise significantly before it reaches the eardrum is a typical first step for headsets/headphones designed to reduce noise as that reduces both the noise and required cancellation signal.
It seems to me that the easy way for hearing aid users to reduce noise would be to use sound protection muffs or headphones with significant passive reduction. That is typically done with muff/phones that go over the ear and seal completely against the head. I use some old-school large-cup “closed” headphones from Beyerdynamic over my Oticon OPN S1 aids without noticeable feedback. They passively reduce noise by about 20 db which is more than typical consumer level active noise reduction headphones provide.