The French youtuber Deus Ex silicium made a through analysis. Basically, hearing aids are slightly worse than ordinary wireless headphones, but 10 times more expensive.
I wonder if some constructors could target this use-case by making aids that are very easy to self-calibrate.
On the other hand, the median hearing aid user is pretty old, has lots of disposable money and has never watched a youtube tutorial in their life, so it might be a small market.
Not to mention, it probably takes a couple of years to get the certification for a device. So, any device to market is easily 2-3 years old tech by definition.
Approval can be quicker for hearing aids as there are already works-alike devices on the market. 510(k) clearance takes less than 6 months.