>But if you already have a secure channel - what's the use case?
You can use Whatsapp, or some other E2E-encrypted service that is easy to use, and then transmit the sensitive data over encrypted email, which is more convenient for long-form text.
You can use Whatsapp, or some other E2E-encrypted service that is easy to use, and then transmit the sensitive data over encrypted email, which is more convenient for long-form text.