I have been using the nitecore thumb in red mode clipped to my shirt when I am running. It seemed to be a perfect light for that… lightweight, good clip, long battery life.
But it died in light rain, so I was hoping to find something similar which is more water resistant…
I don’t think i can offer a sound advice since i’m not running, but maybe you should check biking lights. I see bikes passing by with a flashing red light clipped at the back or on the rider backpack for instance. There may even be similar running lights that recharge when running?