Inject dynamically commands into a deployment
This question is more rather more about an option on how to scale certain services in Kubernetes. I think the best pattern for this is to have a Kubernetes Operator. Essentially, this would manage the lifecycle of your nsqd application. There are several operator tools that you can use to create your nsqd operator:
A good example of a scale-out operator is Srimzi which is Kafka operator for Kubernetes.
You can also find other well-known operators in the Operator Hub.