How do I find out EXACTLY what needs to be updated so that my Mac will "properly" recognize my iPhone/iPad?

Yeah... what it says. (I'm sorry, this is frustrating).

Catalina on the Mac, latest iOS's on the devices. Connect it to the mac for syncing, I get the window saying that a software update is required bah blah blah... The last time this happened, I was on Sierra, ignorantly clicked on Install, and lost usability with all of my audio/music production apps, despite that the Mac OS showed that I was still on Sierra. According to one of the developers, the update changed something in the audio that rendered the applications unusable, necessitating costly upgrades to get things working again. I wasn't the only one as they had many calls from users throughout the day that had done exactly the same thing.

Understandably, with Big Sur lurking around the corner, and my apps NOT currently compatible, there's no way I'm going to do any sort of upgrade without knowing that my apps will still work. Hence, the need to somehow learn EXACTLY what needs to be upgraded with the Mac OS/Catalina so that my iOS devices will properly sync.

Thanks in advance for helpful info.

James