I’ve gotten Möbius set up in the meantime and it’s quite promising so far. My core use case works, which is syncing a few markdown files between my Mac and iPhone, so I can edit with Vim in the Mac and iaWriter on the phone, keeping them in sync as I do. This has so far been impossible for me to set up in any usable way (without resorting to Dropbox or iCloud), so syncthing and Möbius are really looking good.
Here are a couple issues and questions I’ve run into along the way:
I suspect severe itch-scratching based development in many cases: developers who develop things that works for them tend to use real computers, whereas the general population don’t even buy laptops any more.