Damus has allowed you to see someone else’s pubkey for a while now. Having a single client implement encrypted sent and received timestamps isn’t the answer, you would need a NIP. Nostr is completely public so there’s no good way to send encrypted DMs on a public relay because others could check when the message appeared on the relay. The best option IMO is to just use a private relay for a private conversation. Companies could have their own relays just like they have their own Slack channels.