Not to my knowledge! Sometimes you’ll see a handful of OW characters at a panfan community, but that’s about as close as you get.
I feel like the hang up is determining a canon point from which to start. There are so many characters who havent actually met and have no reason to interact with each other, which could make a large group setting difficult to coordinate. An au scenario like Junkenstein’s Revenge could work, or maybe something during the Retribution era before Overwatch disbanded and the majority of characters went their separate ways?