Hi Dhruv,
Currently, we don't have support to detect scrolling in Picker to achieve your requirement. We would like to inform you that we have considered this as feature request “Provide scroll events supports in Picker” and you can track the status of this feature implements through the below link.
Please cast your vote to make it count. We will prioritize the features every release based on the demands, and we do not have an immediate plan to implement this feature since we committed with already planned work. So, this feature will be available in any of our upcoming releases.
If you have any more specifications/suggestions to the feature request, you can add it as a comment in the portal.
Regards,
Jeya K