How to allow local network traffic while VPN with global option to block non VPN traffic is on?

How to allow local network traffic while (Wireguard) VPN with global option to block non VPN traffic is on? Asking for firmware 4.x.

It needs to modify the code to do this:

sed -i  's/"$killswitch" = 0/1 = 1/' /usr/bin/route_policy

apply the policy:

/etc/init.d/vpnpolicy-apply start

This only works with MAC or VLAN VPN policy. DNS query to bypass VPN is still blocked while using domain policy.
We’ll evaluate to improve the design in firmware 4.6.