I just started making wine from store bought fruit juices. My first 5 gallon batch made from fake-strawberry juice is going very well and tastes really good so far (just snuck off a little bit
2nd batch is from a concord grape juice but it's a bit sour tasting.. luckily it's not flat, but I think that's the nature of concord grapes.
my only regret so far is not having an acid titration kit to measure them before jumping in. That's the next item on the list because a few of the 1 gallon experiments have turned out pretty awful tasting
(gallon of dollar store apple juice turned out very sour, totally flat and nasty.. maybe it needed time but I don't think so ? )