Bunch of media apps and whatnot have a share feature to allow someone to listen to what you’re listening to from their own device, but a few of them are advertising it with people physically hanging out together using it. Man, if they are ij the same room and have their own headphones, they can just connect their headphones to my phone and we both listen to the song at the same time from the same player. AFAIK, there’s not really a limit to how many devices you can connect via bluetooth. I know you can get at least 3 headphone sets going on mine before it starts to lag a bit.