There is a long running joke about open source software that it is almost always a paragon of poor UI/UX. If you have ever struggled with software on linux you know that sometimes it can be impenetrable. I don’t blame developers, UI/UX is hard and when you are the same person developing and testing it, it is easy to forget that works for me may not work for everyone else.
This is sort of how we need to think about accessibility. It is really hard to understand how someone else will use it if you are used to always using your app one way. With that in mind I recommend other developers use the Accessibility Inspector and Voice over to get an idea for how accessible their software is.
I have made several improvements to the next Mac release to address issues with accessibility. The elements of the UI should have descriptions and help text where applicable. You can now navigate through the conversations list and quickly hear your messages, who sent them and where they came from. I will keep improving in future update (and check iOS as well ) let me know how I can make this better.