Hi snmark!
Re: "Hearing aid access on Apple Watch for calls/messages?"
As Apple users in the community, just as you are, it is likely no-one here knows much more, if any, about what Apple will or will not do in the future, than you do.
We mostly find out such things at the time they are made public.
We can find out what information Apple releases by going to the Apple newsroom website:
Eg: In the May 19, 2026 Press Release article below
Apple unveils new accessibility features, and updates with Apple Intelligence - Apple
Amongst the new accessibility features: Apple says:
- "Made for iPhone hearing aids pair and hand off between Apple devices more reliably, with an improved setup experience in iOS, iPadOS, macOS, and visionOS."
Sorry that the WatchOS is not mentioned.
If you'd like to watch out for future press-releases, or browse past ones: Here's the link for the Apple Newsroom itself: Newsroom - Apple
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Re: "... it’s quite difficult to hear messages and calls from the watch speaker."
Some time ago, (published April 26, 2023), a third-party (non-Apple) website provided tips on using hearing-aids with Apple Watch: The article would likely be quite out-of-date with current usage, yet it may still be worth browsing through for tips:
How to use your MFI hearing aids with your iPhone and Apple Watch
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Re: "I hear all messages and calls to my phone through my hearing aids and it would be excellent to have the watch do the same ... "
If you wish: You can also send a "feature request" to Apple via their feedback website: (You could include a link to this discussion if you want, as Apple is unlikely to see your question here in the community.)
Feedback - Watch - Apple
All the best :-)