This is kind of wide question, I found many information about this topic.
Possible technologies
Neither of these does currently have a fully-implemented peer-to-peer library, or I haven't found such.
In fact I'm not interested in any kind of gaming library (and I don't target such issues)
Questions I'd considered
GameKit is compatible only with other GameKit
I'd like to efficiently communicate between as many devices as possible, without need of using mobile data (3G,HS*PA,LTE) or WIFI AP as intermediate point.
And not connecting people over large distances, really just like a PAN over Bluetooth.
Thus, what features I'd require to have
Features I'd like to have
Is there currently anything I could use for mentioned features?
I know google just came out with a cross platform api for ios and android devices to communicate with each other. I don't know what you're exactly looking for but this one lets you pass small binary payloads between Android and IOS devices. they don't have to be on the same network at all either or connected to the internet. I'll include the link just check it out.