Adherence to avoiding UPFs, by the current Nova classification, would lead to most people having to radically change their diets, assuming you actually follow the Nova classification of UPFs to a tee. And assuming they're already reasonably healthy, there would be no meaningful health benefits I suspect.

That's precisely what the food product industry wants you to believe.

Potentially there could no noticable health improvements but potentially far less health degradation over time when you think about things like risk of type-2 diabetes with high sugar and high-UPF diets.

But it's true that we mustn't focus only on UPFs but it is looking more and more like a significant factor (even if the definitions could be improved).