There have been alternative (often mad) health proponents who have insisted upon only eating fruit in the morning for years - similar(ish) reasons. I think there is probably something to it.

I remember this being a thing in some Tony Robbins book!

Whole fruit also has a lower glycemic index due to the fiber. This slow release of sugar helps reduce insulin resistance and balance out hormone response in general.

Hormonal imbalance is severely underrated as a root cause of common mental health issues like anxiety, depression, etc.

Having fruit in the morning is a little boost without the guilt. Adding in some light exercise, like walking, also helps prime the day. It even gets easier to wake up early for all this the more regularly it's done. It's one big reinforcement cycle for healthy habits.

I mean the most obvious reason is fibers