I've had a similar experience, but only once, and only induced as an accidental side effect by months of mental and physical preparation. About ten years ago, I spent three months where I almost singularly (outside of my software job) thought about and prepared for a powerlifting competition (amateur, not crazy strong). This would be my second competition (and at the same location), and every night before falling asleep, I would visualize the entire day, from waking up, to driving to the location, weighing in, sitting in the stands, walking up to the platform, and completing the lifts. What I would be wearing, what I would eat, what books I would bring. What lifts I would attempt, and how I would warm up.
During the competition, while I was on the platform, I felt like my consciousness was ten feet above my head, and all my actions happened autonomously, without any conscious direction. I can hear, on the video someone recorded, my father yelling my name from the stands, but in the moment I had no conception of that. I bumped into the spotter while resetting my stance on one of the squats, and didn't even really register or respond to his presence.
It felt incredibly powerful, but that's probably because of all the purposeful preparation that led up to it. I can't imagine how terrifying that would be to have happen at random without any warning.
Do you lose muscle control? I imagine you'd still be walking around the grocery store, just without a sense of agency of which steps you take, right?
Somewhat unrelatedly, I've recently been toying with a philosophical idea: what is the inverse of solipsism? Solipsism is the belief that the Self is the only real thing, since it's the only thing that can think. Everything else, and everyone else, may all be false perceptions. So I am real, and everyone else is a figment of my imagination. The inverse of that would be that everyone else is real, and I their collective mass hallucination. Who am I to say that I exist? The best way to exist is to not believe in one's existence. I wouldn't say I exactly subscribe to it, but I do enjoy thinking about it.