Technically Briar doesn't have any kind of signup process, it's only asking you to choose a nickname and a password that will be used to encrypt the content sto

Technically Briar doesn't have any kind of signup process, it's only asking you to choose a nickname and a password that will be used to encrypt the content stored locally (and securely store the encryption keys). The nickname is only an arbitrary label shown to other users (multiple users can have the same nickname, but they'll have a different procedurally-generated avatar tied to the actual unique ID). You can literally type in anything, since there's no server that validate that info.