You are correct, ios will still work, however new users or people that didn’t use 1.5.1 in the past might not have this. I for one don’t have it I believe as I haven’t used the 1.5.1 app ever since 2.0 was in beta.
Also I have to mention that I made that specific post a few months back when it was still in beta. You don’t have to do the fake notification, but I believe it is also mentioned that you should only attempt that if it isn’t working (and in the beta period this would often be the case when using actionable notifications for the first time with the “old” ios config)
The only reason I share this again because this method has worked 100% of the time for me and all devices I have set up in the past.
When coming from beta, I will still suggest to remove ALL integrations regarding the mobile app in HA, restart HA and then reinstall the app and start the onboarding process again. (Then after onboarding restart HA while the app is open so it can register the mobile_app notify service, which is not there after onboarding).
Ofc a lot has changed regarding the app, but following these steps should theoretically make it work unless there are other problems.
Edit: still, it wouldn’t hurt to try . Maybe it will solve his problem. Sometimes these kind of things are found on such simple solutions. But like I mentioned I can’t guarantee that it works for him. It worked for virtually everyone I had set it up for in the past so who knows.