Is there a way to trigger a function with clickOpens?

[pyronlaboratory]

Scenario: I've set two date pickers for Start Date and End Date

If Start Date is not selected then, I've disabled End Date using a boolean expression with clickOpens config option. Working great 👍

But I want to invoke a function to generate some kind of an alert for the users to select Start Date first. Any idea how can we achieve this, either by clickOpens or any other props/hook/event?