I’m in Canada. I have an iPhone 15 Pro and an old iPad, both with 18.3.2. Also have Air Pods Pro 2.
As widely reported by others, the Hearing Assistance features are not visible.
Last month, I went to Florida. Upon arrival, I turned on the IPhone, took Air Pods out of the case, put them in my ears, and opened iOS Settings. The AirPods item had appeared in the list. Opened it, and as if by the magic, the Hearing Assistance functionality had been enabled! I was able to do a Hearing Test. The test reported “little to no loss”. (Odd, since my wife insists that I often don’t seem to hear her very well…). After completing the test, I was able to activate Media Assist mode, which I assume applies some equalization to the audio output when listening to music, videos, or calls. However, there is no button to enable Hearing Aid mode. I surmise that’s because the amount of my hearing loss, per the test, was insufficient.
Out of curiosity, I put the iPhone to sleep and woke up the iPad. Once the AirPods had paired with it, the Hearing Assistance features were enabled on the iPad as well.
i did a second Hearing Test, using the iPad. The results of the second test were almost identical to the first. The two tests results then got synced between the two iDevices (via iCloud), and can both be viewed in the Health app.
Upon return to Canada, I checked to see if Hearing Assistance functionality persisted after crossing the border. It did🥳. Further, I subsequently updated the iPad to 18.4, and was surprised to see that HA is still enabled. I’ve not yet updated the iPhone. That’s on my ToDo list, after doing a backup with iMazing.