The sugar seems to be doing something as well. I've been making cranberry sauce for aaages - with sugar (but a lot less than all the recipes I run across online). Last year I tried making some with the same amount of allulose (which is a 1:1 replacement, both by volume and by weight) for a friend who was coming to Thanksgiving who had T2DM; I wanted to make a version he could eat.

It tastes *exactly* the same, but didn't 'gel' properly. Next time I'll add pectin or maybe throw a quince in with the orange in the food processor (a blended whole cara cara orange is my 'secret ingredient').