Alcohol free & sugar free fruit cake

A fruit cake would not be sugar free strictly speaking, since fruits have sugars, but you can make a fruit cake without adding extra sugar by using lots of very sweet dried fruits like dates, raisins and figs.

A cafe I know has a "famous" vegan no sugar no oil cake which is made of about 50% mixed dried fruits. They use dried dates, raisins and apricots. I would guess that they soak the fruits in hot water for a few hours to get some of the sugar to come out and sweeten the batter.

One of the best cakes I have tried has no added sugar as such - it's sweetened by soaking stoneless dates, then grinding that into a smooth paste to use in the batter. Here's a recipe for that (though I made that recipe vegan using water for soaking and cashew almond yogurt instead of dairy yogurt, so have not tested it as written). If you prefer something like a traditional dried fruits cake, you can always add raisins to that recipe and skip the walnuts.

I never use alcohol for anything, so when I make a fruit cake recipe that is supposed to have alcohol, I just skip it. Alcohol is used for soaking fruits to get better extraction than with plain water. Grinding some of the soaked fruits to a paste, as in the dates cake recipe, gets around the problem of water not extracting enough sugar from the fruit to sweeten the batter.