What I am about to write here is similar to third hand information. I do not have first hand experience. I looked into putting an audio loop into a venue.

What I am about to write here is similar to third hand information. I do not have first hand experience. I looked into putting an audio loop into a venue. I asked an audiologist about the prevalence of T-coil equipped hearing aids. She told me most users prefer small and rechargeable. There is not much space in the unit and rechargeable would likely be selected. So, the T-coil does not get included. She thought T-coil units were common in Europe. There are special amplifiers to drive the audio loop. The makers don't tell us much about them. I think we would call those transconductance amplifiers. Reading the subject article is encouraging. Perhaps we will just try this after the virus is not such a threat.