Respectfully, I cannot disagree with you more on the part about "if they were identical there would be no point in having 2 different operating systems". To be frank, I found this comment condescending (perhaps unintentionally) and just false.
This is not an operating system issue, this is a user design issue. The operating system is capable of running the sound and haptics independently and jointed. What iPhone is not doing, is enabling the user to decide when it makes sense to have one or the other combined or not combined. Android has this 3 settings as a stock, defaulted, quick access through the physical buttons, option and I have found it IMMENSELY useful over the years prior to my switch. It was not a feature I expected to loose and I miss it greatly.
I do not want my phone yelling at me all the time, but sometimes I am expecting an important call where I do need it yelling at me at full volume. However 95% of the time, the simple vibration is enough to get my attention to check my phone without disturbing anyone else around me. Now I miss many messages because I do not want the phone to go off all the time so I am forced to keep it on pure silent due to this design flaw. Not including this third option is such a blatant oversight that it is baffling.
Thank you for providing the Shortcuts references. Perhaps I will check into that more closely (but I would argue, I should not have to in a well designed product).