Have gmail.com support NIP 05 😂

Simple forwarding would work, but would expose the destination email and confuse senders. Bi-directional forwarding (with a reply-to that points to the proxy) would work, but would potentially mess up users' contact lists. Email is just kind of gross this way, there's no way to pick up your identity and move.

The reverse could also work; emails sent to someone's NIP-05 could go to DMs and vice versa. Or someone could build an email client that supports that flow, but then that's just another email service.