Looking again at this thread now that I am completely unable to use RPD because of a weird new bug, possibly caused by Wayland (see 1031557).
I have actually tried to use this, somewhat naively, to import photos from my phone which are sync’d to my local disk with syncthing, but that doesn’t work for my case because gphoto doesn’t find those pictures at all… It assumes an SD card or some camera is connected to the computer…
I think my next step is just give up on the “roll name” workflow Darktable somehow imposed on my and just batch-import everything in a YYYY/MM/DD tree. The last photos I have properly archived at all are from April 2021 at this point, almost two years. I have 25GB of photos on my phone and an unknown quantity in the camera. I need a stopgap fix here…