There’s no way to have drillPick itself ignore the values. You would have to increase the limit and then filter them yourself. We may eventually have such a capability, but I don’t have an ETA.
You can check if the item in the drillPick is a Label or LabelCollection primitive and ignore it.
There’s no way to do this yet, though we may eventually support something similar. One workaround would be to add an extra property to items you want to ignore and check if that property exists in your picking code (and ignore it there).