I've also seen them called towel ponchos, changing towels, surfer's ponchos etc.
E.g.
http://www.robierobes.com/buy/buy-robie-original
https://www.turkish-t.com/products/seashore-poncho
I like the idea of using one after swimming laps at the pool. Going back to the changing cubicles I'm always freezing, so they seem like a good option for that.
If you use one: do you actually use them to dry off or just for warmth/coverage?
I like the idea of not having to schlep along an extra towel, so if a robie can function as both a towel and a cover-up that would be ideal.
I like the modern look of the one in the second link. Would love to hear if you have other stylish suggestions.
Thank you!