Reference the load balancer selector value in selector rule

I’m trying to dynamically route requests to a service using a rancher load balancer selector rule.
The selector rule is configured with a wildcard request host name:

At the time the target service is being created the label could be set to something like “” in order to match the selector rule in the load balancer.

Is there a possibility to reference the request host as a variable to allow such dynamic routing? Or is there another possible solution without adding selector rules via API for each target service?