>It just isn't that useful for dealing with photos taken with a separate camera.
I recently went on a trip with no laptop -- only my "real" camera, my iPhone, and a Western Digital MyPassport Wireless Pro: https://www.wdc.com/products/portable-storage/my-passport-wi...
It worked out surprisingly well. I mainly bought the MyPassport for the extra storage space so I didn't have to bring a million SD cards, but it also worked well as a backup battery pack for the phone, and for transferring a few of those images to the phone for immediate access. Admittedly, I shot in RAW + JPEG and the app only recognizes the JPEGs (from what I could tell quickly) but it was good enough for the few photos I wanted to share right away after taking them.
I don't have an iPad but I've been considering one just for photo editing with the pencil. I hear Lightroom on iPads is getting better, and I just got an e-mail today about Affinity Photo being released for iPad.
But yeah, consider the WD MyPassport if transferring/storing photos without a true laptop was a problem.