I’m transfering data from my phone to an extrernal hard drive which I connect to my laptop. To do the syncing a bit more automated, I’ve written some WinSCP scripts. I create a local hostpot with my phone, I connect my pc to it and then I move files. (My phone has a dual wifi antenna which allows to have both the hotspot on and connect to my wifi, so I can post this comment without using data.)
The data I transfer are ~all sorts of types; Media files (either from my camera folder or various other folders), text or similar files (I also keep logs of the files on my device to help me restore stuff), encrypted files, backups of apps+data/phone settings/contacts/sms/calls etc. At the moment of writing this I’m transfering about 30-40gb to my pc as I slowly prepare myself for the factory reset.
My workflow is far from automated, but I’ve made a lot of progress since last year with the help of the scripts. It’s sad though, because backing up and restoring everything now takes about 9hours, while with an sd card I could reduce it to something like half an hour… My next phone will probably be fairphone 6 or 7 in 2028 (now I have a xiaomi mi 10 running custom roms) if it has an sd card slot.