I think it should be very useful. Tablet is very useful for creative writing, especially with an external keyboard.
Sorry there isn’t and I don’t expect that there will be in the foreseeable future.
FT2 works with text files, meaning you can use a broad range of iPad text editors. I’m particularly fond of Editorial because it operates in a very similar way to FoldingText; for all my exploration thus far, it’s the closest comparable companion on iOS that I’ve found.