On MacOS of that era, the files didn't even show up in the "Open..." dialogs of those other apps. Many of those apps didn't have a "Show all files" option.
Oh, I didn't realize it was that rigid. Yeah, that's an unfortunate system.
Isn't iOS still essentially the same way? It was one reason I stopped using iOS devices as I frequently wanted to open, for instance, pdf or image files from multiple apps.
Does IOS even have a file system? Last time I used it, I had to share files back and forth from one app to others just to open them. It was really annoying...