Other than carbs nothing really would provide a noticeable increase in endurance during your workout.
I'd choose BCAAs specifically something like Intrablast by Nutrabio. Not a true BCAA as it also contains EAAs and betaine, but made specifically for intra-training (hence the name).
Ergonine. BCAA aren't needed if you are hitting your protein intake with food or powder. The ingredients in Erognine have too many benefits.
I'm working out fasted, so hoping an intra may assist in slight boost in performance, even if only physiological!!