How P2P chat works in byteball? Is it some kind of "onchain" chat where all messages encrypted and stored in DAG?
Can it be used to chat with anyone in the network or it's restricted to my own devices only?
Not stored in DAG, encrypted and traverses Byteball network, looking for its destination, stored at hubs for a configurable amount of time. You can chat with anyone, if you haved paired previously with the other device/person before - otherwise spam would be a problem.