Sugar.
Maltodextrin from the home-brew shop is apparently the go to, for in the bidon. I take a teaspoon of cheap aldi jam every 15 minutes, when zwifting, and just mung on natural confectionery company snakes, when out on the mtb. Don't overdo it, but don't underdo it either.
100% this. If you want an easy way to experiment Coopers Home Brew Brewing Sugar & Brew Enhancer 1 & 2 are different blends of dextrose and maltodextrine and are available from Big W for about 10 bucks, in Vic and SA at least.
Dextrose is similar to table sugar, maltodextrin has all the energy benefits of sugar but isn't as sweet. You can use plain table sugar but it's pretty sickly and syrupy.
Gatorade/Powerade/Staminade are all just powdered forms of sugar with electrolytes and flavours, but you can mix it to your own strength. I'm coming at it from the performance perspective and adding maltodextrin to the staminade mix.
Don't stress about loading up sugar while you ride, your muscles run on simple sugars, glucose in particular. Plus, if you fuel your ride, you can ride longer and get the benefits of more exercise.
And the zone 1/2 thing is right, but it's more a sliding scale, not a switch. And you really need to ride long enough to put a bit of strain on your body, for some that's half an hour, for me is about 4. Then refill with clean food.