Just in case someone searches this in the future.
I've dug around a bit more and the answer is MAYBE!
Wood Rat offer ultra fine dovetail bits with both 8 degree and 9 degree slopes. I can see how the 8 degree ones might be used with Leigh jigs, but I can't see how the 9 degree ones could be used. And that's for through dovetails, I'm still unclear what the situation is on half-blind dovetails.