The choice of whether to open or import files is an important decision in Affinity iPad apps. Understanding the difference will help with file management and backup strategies.
You can open Affinity documents, as well as Adobe InDesign, PDF, Illustrator and Photoshop documents into Affinity Publisher.
You can open previously saved Affinity documents from local or cloud storage. When opening, the key point is that these files are kept in their original location and will be overwritten on saving.
Unlike opening, importing always makes a copy of the original document and loads it as an 'internal' document; you cannot overwrite the original file once it has been imported. Imported documents must be saved as an .afpub file. The imported file could be from Apple Photos library or your local/cloud storage. On saving, the document can be saved to anywhere on your local or cloud storage.
Recent documents are shown as thumbnails at the top of the Home screen for your convenience. They are actually open minimized documents, so saving and closing a document will create a physical file and remove the document's thumbnail from the app's Home screen.
Alternatively, you can drag-and-drop an image or document from the Files app directly onto the Home screen to open it.
You'll be prompted to resolve any missing files as you would when Opening documents above.