Maybe, like me, you're tired of typing a password and prefer to disable password auth for ssh anyway. Maybe, like me, you want to point VS Code at your Edge Router and be able to read configs and things. Maybe, like me, you'll discover that VS Code's Remote-SSH extension doesn't support the ERX architecture and be mildy bummed, but still happy to have passwordless SSH (via ssh-agent) and know that no password will get some rando into your ERX.
Here's how.
Cribbed from the VyOS Login/User Management docs