Smartphone hearing aid application -- 2

I want to develop a smartphone hearing aid app for people with hearing loss.
A hearing aid app that uses a smartphone and regular earphones to cancel out noise and allow the user to hear the other person's conversation rather than their own.
The hearing impaired person can adjust the volume of the conversation on the smartphone according to the degree of their hearing loss and listen to it through the earphones.
The earphones connect to the smartphone via Bluetooth or wired.

There are two requirements.

First, there is a previously released hearing aid app with a similar feature called "EarBoost".
For example: https://earboost.jp/
This app first measures your hearing and then sets the gain automatically, so you don't have any control or know exactly what the gain is for each frequency.
So I would like to remove the audiometry and enter the gain manually instead of setting it automatically.
The gain should be expressed in db and should be adjustable at the following frequencies: 250Hz, 500Hz, 1000Hz, 2000Hz, 4000Hz, and separately for the left and right ears.

Second, latency should be reduced as much as possible.
Latency is one of the fatal flaws of earbuds.
When watching movies or listening to other people's voices, the latency is fine, but when talking to yourself, the delay in magnetization is very annoying. This latency must be solved. The design may be similar to the ear boost, but it shouldn't be inferior in performance.