I don’t think there is multi device paring bluetooth transmitter.
There is this system https://www.listentech.com/product-category/wi-fi-streaming/
That system is an audio encoder that connects to either a stand alone WIFI router or the buildings WIFI network, anyone with a phone can download the app and with their phone connected to the WIFI network the audio is streamed to their phone and from their phone they can bluetooth to their hearing aids.
Yes it does require some smart phone usage level of operation.
I’ve installed a couple of those systems and they do work well.