I'm pretty sure homebrew has a save game extractor and an installer, so you can pretty much copy and rip any save game file onto your SD card. I haven't tried it out to see how it works, but I haven't seen anything saying it doesn't work, so it sounds like it should be pretty basic coding.
A lot of times, developers don't even think about how one person can play the same game on multiple consoles, though. It just gets overlooked.