When assigning interfaces we can also add gateways to them. This would offer you the chance to balance traffic via different VPN providers or do more complex routing scenarios.
When assigning interfaces, gateways can be added to them. This is useful if balancing traffic across multiple tunnels is required or in more complex routing scenarios. To do this, go to System ‣ Gateways ‣ Single and add a new gateway. Choose the relevant WireGuard interface and set the Gateway to dynamic. These scenarios are otherwise beyond the scope of this how-to
But true HA / LB is not possible with WG (yet...). So all connection states will be dropped when having a failover-event.