Allow Basic Port Forwarding With Network Load Balancer for all Services
Azure Network Load Balancer should support basic port forwarding, many customers have firewall rules that block PaaS Services. Today you can create a port forwarder with NLB, but only to its supported endpoints. Ideally you could forward to any Azure hostname or IP address.
Sorry, this is not possible with Load Balancer as only VM or VMSS can be destinations. If your traffic is HTTP/HTTPS, you may be able to use Application Gateway instead. Or you can use a 3rd party appliance to proxy traffic.