Briar both parties have to be online since there are no servers. it's pure peer to peer
Yes, that one I know, though my concerns are about the code and the implementation, the tradeoff made by each. I like that with briar I can use it in a place where I don't have internet though I need to be near, but it is designed for such a scenario afaik, like a protest or something like that But SimoleX is just perfect UI and UX, also they seem to be legit 😬