This is probably asking the impossible from a (rotten) Apple device, but here goes...
I want to help someone backup some very long Whatsapp chat history, there's the "Export chat" option which creates a huge file which then can be uploaded to Onedrive or wherever, if you have a few hours to leave your phone doing this.
Instead, I'd like to just save the file on the phone, and then move it to a PC via USB (or maybe local WIFI). Apple lets you copy your photos via USB, maybe there is an app that makes other files visible the same way?
I have tried an app called Airtransfer for a wifi method, but it didn't work, the file arrived empty. Maybe there is a trick i missed.
Any suggestions welcome.