OT/
Before posting images on the forum, please kindly consider this.
/OT
Here is an older discussion (from 2017), in which @unman suggests a way to attach NICs to a VM. You can check /etc/xen/scripts/vif* for current existing scripts.
Once you have a second NIC for uplink connection, you will need some form of routing. Setting up a load balancer is non-Qubes-specific and I can’t help you with that.
It would be interesting to know your results.