CLI (copy-paste)
Paste these commands at the VyOS prompt (1.4 or newer), not in configuration mode. They add the WireGuard interface wg707 with the VPN as its peer and the routes to the servers, then commit and save; if wg707 is already there, they change nothing. If the input firewall drops everything by default, allow UDP to the listen port and the traffic from the servers on wg707.
if cli-shell-api existsEffective interfaces wireguard wg707; then
echo "Stopped, nothing was changed: this router already has an interface named wg707. If it is not this site's tunnel, use another name in these commands."
else
W=/opt/vyatta/sbin/vyatta-cfg-cmd-wrapper
$W begin
$W set interfaces wireguard wg707 address '<tunnel address>/32'
$W set interfaces wireguard wg707 private-key 'PRIVATE_KEY_FROM_THE_CONF_FILE'
$W set interfaces wireguard wg707 peer vpsnet public-key '<VPN public key>'
$W set interfaces wireguard wg707 peer vpsnet address '<your VPN address>'
$W set interfaces wireguard wg707 peer vpsnet port '<VPN port>'
$W set interfaces wireguard wg707 peer vpsnet allowed-ips '<server address>/32'
$W set interfaces wireguard wg707 peer vpsnet persistent-keepalive '25'
$W set protocols static route <server address>/32 interface wg707
$W commit
$W save
$W end
fi