Question : How to "dynamically" set labels for taking decision in Manual Judgement stage, and subsequently how to use the option selected in Manual Judgement stage by downstream stages.

Answer:  These links might help:

https://www.spinnaker.io/guides/tutorials/codelabs/safe-deployments/#adding-a-manual-judgment-to-deployment-pipelines

https://www.spinnaker.io/guides/tutorials/codelabs/safe-deployments/#changing-pipeline-behavior-based-on-selected-judgment