GCP currently as the only cloud offers full username customization for SSH keys. We have decided to hardcode the username to `gcp-user` similarly to `ec2-user` on AWS.

But going forward, we might want to allow our users to customize users from the portal. To do this, we would need to add a username to pubkeys and use that. For AWS/Azure we might actually add a cloud-init config that configures the SSH key both to the standard username (ec2-user) as well as newly created user (with sudo).