When will iPhone Separate Notification Volume from Ringer Volume?

Hi,

I had a [cough, cough different brand] phone for many, many years where I could keep my ringer on HIGH volume and my notifications (texts, emails, etc.) on LOW volume at the same time (wow!) and it was such a marvelous feature!!! (Yes, I am aware of being able to SILENCE notifications on iPhone for a certain time, group, or app, etc., but this is not the fix I am asking for or wanting).

I love being alerted to both, but definitely want notifications (usually NOT time-sensitive; usually much more abundant) to be less obtrusive than phone calls (usually time-sensitive, of more importance, and way less frequent!).

When will the seemingly standard, basic feature of being able to adjust call volume vs notification volume be added to iphone?

Thanks!