Potato chips, which I won't indulge in otherwise, are excellent when it's hot. Sodium, potassium, plus of course carbs. Check the package - nutrition varies with brand/variety.

Hard boiled eggs with salt + banana is good too.

I drink water or iced tea with them.

I didn't see any special benefits from powders and sports drinks (for me) after trying them for years, and usually the taste is not so great plus it's one more thing to have to plan out for a ride.