I'm sorry I cannot provide any useful answer to solve your problem "right now", but I bought the latest third generation iPad Air a few days ago with the premise of the release of iPadOS13 this autumn, which will make the handling of the files as easy as on normal computers, PC or Mac.
On iPadOS13, you (we) should be able to connect a USB card reader via either the Lightning-USB Camera Adapter or a USB-C cable and import or export image files.