Openconnect website does have a chapter called "Running as a non-root user".
However, if you read it more closely, you will see that it does not answer the question of how to run
openconnect as a non-root user. You ether need to call
/etc/vpnc/vpnc-script as a root, or you need to use
ip tools, which also require root access. In other words, you'll need root access one way and the other.
However, there are legit use cases when we need to grant a user the ability to connect to a VPN, while we still don't want them to have full root access.
How do you cope with that?