When speaking six months back with Oticon support about Bluetooth 5.0 and BLE that are now available on Samsung S8 devices, Oticon said they cannot work with that platform as there is no audio specific protocol that works with BLE and its software stack is not consistent across all platforms.
I was quite confused at the time until I read this recent Wired article about iPhone and its unique BLEA protocol, a variant of BLE that has audio paired.
This is the result of the Made for iPhone designations that we now see on many hearing aids brands today. It seems that from the article that Apple has probably chosen to make its BLEA protocol closed source due to its reliance on hardware and software algorithms only available on its iPhones, rather than open source the protocol to the Android platform.
Also, the article mentions that Google has not focused much time on developing this protocol and has instead focused on closed captioning. From Google’s standpoint, this may make strategic sense given its assets of YouTube, Photos, etc. that billions watch rather than focusing on hardware/software standardization to develop a BLEA protocol that millions only will use.
TLDR version Apple developed its own proprietary protocol for hearing aids and didn’t share, and Google hasn’t responded accordingly for various reasons. So hearing aids manufacturers are probably waiting for Google to step up its game with its own protocol.