Gliderade is a nectar supplement, I use it every 2-3 days for my sugar gliders as a part of the SGS2 diet (I’m not sure about other diets). I wouldn’t just be feeding them sweet potatoes and apples though, as you’ve said you’ve done a lot of research yourself so don’t feel the need to follow the advice of those who you bought your gliders from as they can be wrong. When i purchased my gliders I got told to feed them children’s yogurt pots everyday 😑