Yes, bearded dragons can eat red grapes once in a while as rare treats.
Bearded dragons like all reptiles need a diet that’s low in carbohydrates and high in plant protein (like animals).
Red grapes also contain sugars, so it’s bad for bearded dragons to have them more than occasionally. These sugars are what makes grapes healthy to eat, but they’re bad for bearded dragons.
Red grapes have fiber and water in them which is good for bearded dragons because they need both of those things.
Bearded dragons are omnivores, so they eat plants and meat/animal protein.
Red grapes have some vitamins that are good for bearded dragons like Vitamin K, Vitamin C, Potassium, etc.
The most important things in red grapes are sugars which are bad for bearded dragons.
Sugars give the body energy but too much can cause health problems.
It’s important to remember that too much of anything isn’t good.
Too many carbs are bad for bearded dragons, so it’s not recommended they have red grapes more than once in a while.