@nap, you may be interested in this related discussion where members discuss various mask solutions compatible with hearing aids.
- Coronavirus facemask interferes with hearing aids https://connect.mayoclinic.org/discussion/coronavirus-mask-interferes-with-hearing-aids/

There really isn't a perfect mask for people who use hearing aids. You have to figure out what is comfortable for you, and make sure you are aware of your personal hearing devices when you remove the mask. I prefer those that tie behind my head, but others find those uncomfortable. I often put on a baseball hat when I need to don a mask because it helps hold the ties in place. Others have said they don't wear hats. The window masks should be worn by other people who work with or socialize with us. We don't need those unless we are with other people with hearing loss. They keep advertising them 'for deaf and hard of hearing people', but they are to help those people by having others use them. 🙂