CORRECTION!: It worked! The iPhone with iOS 14.6 is no longer "(unsupported OS version)" in my Xcode 12.4 on my Catalina MacBook 2012.

And it seems very dishonest, that Xcode is just eternally saying "iPhone is busy: Preparing iPhone".... That's bullshit....

Isn't it funny - or maybe ridiculous - that when I express exactly what I feel about this, Apple substitutes it with "********"....

I think it's sad that a newer iPhone 12 mini running iOS 18.1 connected to Xcode 16.1 without problems.