To support people who have multiple inboxes with other providers and are in the process of switching to Proton, we’re evolving our Forwarding feature. Soon, you’ll be able to send and receive emails from your existing Gmail email address directly from your new Proton Mail inbox.

This is really important for migration of existing users. I’m currently doing it with alt ident in Thunderbird but that requires Proton Bridge running on my infra. For family and friends, this should be a feature native to Proton Mail itself.