It can work with simplex channels if you have the public key of the receiver. Both parties just need to know each other's public keys to create encrypted commun

It can work with simplex channels if you have the public key of the receiver. Both parties just need to know each other's public keys to create encrypted communication. After exchanging the public keys, it can be one-way communication. I guess it wouldn't work for a one-to-many channel though, just individual one-to-one channels.