I've no problem through the Accessibility Menu on my iPhone, pairing my Signia Stretta hearing aids. But my MacBook Air and iMac have no such menu option and the Bluetooth menu doesn't discover them.
MacBook, macOS 10.13
my impression is that most if not all hearing aids that support bluetooth use the bluetooth protocol called a2dp
List of Bluetooth profiles - Wikipedia
like all bluetooth headsets and bluetooth speakers use, so if that is the case then you just pair it like any other bluetooth headset
How to connect Bluetooth headphones to a Mac | ZDNET
or
Connect a Bluetooth device with your Mac - Apple Support
of cause first time one connect a bluetooth device to a computer one needs to place the bluetooth device into pairing / discovery mode, how one goes about doing so with your hearing aid would probably be in the documentation or on the website of the manfuacturer
ug_nhs-stretta-m-hp-en_rev01_screen.pdf (signia.net)
of cause it could be that they by design limited the airds to mobile devices only
How to Pair Bluetooth Hearing Aids to my iMac
