Yeah, git-annex is very interested in having a special remote for everything and anything. And if someone creates 4 shell commands, I could have a demo working in half an hour. The commands would be:

  lfs-get SHA256 > file
  lfs-store SHA256 < file
  lfs-remove SHA256 (optional)
  lfs-check SHA256 # exit 0 or 1, or some special code if github is not available

Presumably the right way would be to use their http api, but these 4 commands seem generally useful to have anyway.