You can export photos from the iPad to an external storage. I use an SD card dongle (bought from AliExpress) and its companion app for that. I can export selected photo/albums or the whole library. The dongle has USB-C, lighting and USB-A port so works for all devices. With my iPP I can technically export to SSD but I would not do it for few reasons:
- iPadOS sucks when it comes to file transfers of big files or multiple files. No progress bar or some elapsed expected time. You have no idea what's going on.
- iPP storage seems to be slow because file transfers are slower than what I would expect and what I see on my laptop.
- As a whole Flies app is not stable enough and can corrupt files while transferring.
Maybe stupid comment on my part but I doubt that you need to export all files to the iPad. You most probably need few selected files to work on. Here again I prefer to use my SD card dongle than SSD. iPads do not handle well SSD that has way too many files and folders. It is really slow and it takes a lot of time to load. I would usually transfer image files to the SD card (including raw files), I would store them in Camera roll on the iPad and then open them in Affinity Photo. From what I remember Affinity Photo cannot access images from external storage, it has to be stored in Camera roll. Maybe I misremember something though.
This workflow works for few photos but it is not streamline and straightforward and I would not use it as main photo processing workflow. Way too many steps. It does work for few cases where I want to use the pencil to improve a photo though.