Just found your question. Yes, voice isolation works with my Starkey hearing aids … only way to test is to ask the other person what they are hearing (unless you record the call perhaps).
Note that you need to set it per app (phone call, Facetime, Zoom) etc. Helped to reduce the sound of me typing and background noises in the office/home.
Note that you can also use voice isolation on your Mac computer. It really helped for the others on the call who were complaining about background noise. Maybe hearing aid manufacturers can add a similar feature.