As a diabetic, I would love "mirror wheat" which behaves like normal wheat (ie can make breads, etc) but has zero carbs/calories because the body can't digest it. Mirror glucose would be nice too, though allulose is already a pretty close stand in for mirror glucose.
Sounds like a mix of fiber and gluten to get bread-like structure? But then again, if it doesn't deliver carbs, what would be the point?
We already make L-sugars, but they have strong laxative effects.