It seems it's the filesystem that's most costly? Would it be possible, maybe, to store DNG file data, one after the other, on the card, without a filesystem?
But without a filesystem, would it be useful to have DNG files stored on the SD card? Wouldn't you need special software to read off the "packed" DNG data anyway? And if you need special software anyway, couldn't the special software convert the existing raw image data to the DNG format, instead of requiring the hardware to do it?
It's unclear from the website what Photon Transfer does exactly, but from the screenshots it seems it's almost a Lightroom-lite?
A super basic utility that would simply extract the data from the device and spit out DNG files, with zero further processin, would not need to have a nice GUI, or even a GUI at all, and may be enough to lure in Windows users?