There is a bit of a grass roots one, but part of the problem is that it's entirely on the consumption side, as in people deciding to have less sugar. Even proposed legislation solutions involve controlling the consumption side, though at the final product production level.

Which means that sugar producers are still trying to produce the maximum amount of sugar to make the most profit and the lowered demand just ends up driving the price down and makes it more attractive to others to add more sugar. If that lower price is still profitable, then sugar producers can continue full steam ahead.

I've noticed something similar with plastics. Demand is lowered in some areas by legislation (like no plastic straws or single use bags), but plastic is still being produced at volume, so prices go down and other products switch from non-plastic packaging to plastic. I'll call out Betty Crocker homestyle instant mashed potatoes specifically here, that went from a cardboard box containing two paper/metal pouches to a single plastic pouch, which also means it's more of a pain to make only half the package and more likely to create more food waste in addition to plastic waste.

There's a bit of a sugar replacement movement, which isn't necessarily healthier. Most of the sugar replacements have been linked with stuff like dementia if consumed regularly for a long period. And most of them taste a bit off. The other part of the problem is that when you eat something sweet, your body expects sugar. When it doesn't get the sugar it's expecting, it will feel like you are still hungry even though you just ate something.