Back in the day when cameras still took better photos than phones, I've always wanted to backup vacation photos without bringing a computer.
I still remember getting so close with the Google Nexus 4 to being able to connect an SD card reader. It supported OTG, but did not have the required charge pump to supply 5V of VBUS. (Supposedly you could hack together something using a 9V battery, some resistors, and a kernel patch, but that was a bit more than I was willing to risk for the convenience.)
Finally, the Nexus 7 and Nexus 5 supported it out of the box, and while Android didn't offer a FAT32 implementation back then, there was (is?) a USB host API which let apps supply that instead, and I think somebody actually ended up implementing FAT32 in userspace to make it all work!
I had a nexus 7 as a kid, much before I had a personal laptop or even a phone. Used to utilize almost all of these features that most people seem to consider pointless. Had one of the little OTG cables so I could plug in flash storage and keyboards. I remember unzipping APKs, finding assets and trying to change them and rezipping. Only to find out they wouldn't install. Presumably failing a signature check.
Was super cool reading the OP article and finally learning how the thing actually worked with the 5th pin.
I went on a long trip with a mirrorless camera and a SanDisk 500GB portable disk. My "computer-less" backup solution was a Pi-esque machine with USB3 (a RockPi), a powerbank, a card reader, and connecting my phone over USB and tethering it. This gave the RockPi an IP I could ssh into, and I'd ssh from the phone and ran rsync to copy the images from the SD card in the reader to the SanDisk portable drive.
I should make a custom Linux image for the Pi4+ (the whole process is probably too slow without USB3) and some automation (Jenkins?) to do this, I'm sure there's photographers who'd find it useful.
Personally, these days I have less of a need for that kind of thing, given that I can just plug the camera or disk into my phone directly (I suspect a powered USB hub and plugging in both at the same time might even work as well?), but I vaguely recall dedicated "copy everything off this card onto a hard drive" devices being sold, and I don't doubt that some photographers still use these in their workflow.
I've used a microSD reader with OTG adapter on my Samsungs for this purpose for decades now.
Oh, and cameras still take better photos than phones, and it's weird that you would think they don't - they're devices that cost more than phones, designed specifically to take good photos.
I still remember getting so close with the Google Nexus 4 to being able to connect an SD card reader. It supported OTG, but did not have the required charge pump to supply 5V of VBUS. (Supposedly you could hack together something using a 9V battery, some resistors, and a kernel patch, but that was a bit more than I was willing to risk for the convenience.)
Finally, the Nexus 7 and Nexus 5 supported it out of the box, and while Android didn't offer a FAT32 implementation back then, there was (is?) a USB host API which let apps supply that instead, and I think somebody actually ended up implementing FAT32 in userspace to make it all work!