I don't know what I did wrong, but using this as a git difftool (following the config) I didn't get any of the cool things from the demos, I got a weird single-column diff output that only showed the new side of the changes, not a diff.
If I understand your goal correctly, you are looking to especially focus on the visual part of the diff and provide a nice UI for it, and you would like to use OmniDiff as a library?
If so, then let's talk. I have been delaying the design of the API because nobody has a use for it yet, so it is mostly driven by the needs of the CLI/TUI at the moment.
Ping me on my email if you want.