The most accurate description is probably the authors built a hearing aid from the 1960s with only $1 today [0]. Its worn around the neck, doesn't have any fitting, doesn't appear to have beamforming or feedback management, and low amplification.
It turns out these things are all important in clinical outcomes for listening comfort and intelligibility. I've built a modern hearing aid and done extensive patient testing - the details matter and it's not just electrical or algorithm problems but tough mechanical and UX challenges to get something more state of the art.
While I haven't worn many neck mounted devices, the Bose Headphones can get crazy feedback and the feedback path is similar. This would cause squealing discomfort for patients and everyone around them.