I too am looking for a solution for my hearing aids, but with a slightly different need.
I have a Roku ultra as well as a TCL TV. Both of these allow me to use the Roku app on my phone to listen to audio using the app with the headphone listening option. The problem is that when I do that it cuts off the audio for my wife.
what would be great is if Roku offered a hearing aid option on the Roku app where it continued to allow the TV sound to play and at the same time activated playing the audio through the Rocky app on my phone. This way, both my wife and I can hear the audio simultaneously.
I cannot find a way to submit such a suggestion for their software. Maybe they monitor this thread.