But yeah Apple throws the usual concept of a filesystem out the window with iOS, going instead for each app having a walled garden of storage, so if you want to fetch a photo from storage you ask the gallery app to give it to you. For a long time it was not even possible to connect a iPhone to a PC without having iTunes installed. If you wanted to transfer any files it had to be trough putting them in a special sync folder and syncing them across. I found its easier to get files on it by installing the dropbox app and using that. There does exist a cable that converts from Lighting to USB-A host, but back when i tried one of these cables, all it could do is run a import wizard to import photos or music from a USB drive into internal storage.
Your knowledge of iOS is obsolete.
iOS 11, five years ago, introduced a file system manager called (in Apple's usual understated way) the Files app. It works pretty much as you expect. At the top level it shows Locations such as "On My iPhone" and "iCloud Drive" and even "Downloads." You can even connect to a remote server -- see the picture of my iPhone connected to my MacBook Pro.
By default, apps save their files in obvious places, such as Numbers saving spreadsheets in a Numbers directory. But you can actually save files anywhere you want.
iPadOS also allows the use of external storage. If you have an iPad with the Lightning connector, you can use the Camera connector dongle which exposes a USB port and connect USB storage to that, or if you have one of the newer iPads with USB-C or now Thunderbolt-4, the standard cables can connect to USB storage.
So, yeah, if you're going to make sweeping statements about how you can't do this or that, maybe you should find out if what you are saying is true before posting, mmmkay?