Hi Abdul,
I'm not sure how you need to show this information. If it's got to be on the same page as the input, you can use a filter entity on the page. When the user selects the input, trigger a flow to collect the correct data and show it in the datagrid or listview and refresh the filter entity. So the data setup would be:
[Filter entity] (here is where the user would select from a list of employees)
[Employee]
[Employee certifications]
If a popup is allowed, then you could just use a popup page instead of a filter. The user could choose the employee, and a popup with their credentials could be shown.
Good luck!
Belle.
You could use a listview with a listen to widget, in the listview you show all the employees, in the listen to widget you retrieve the certificates for that user in a list. That should get you what you want.
Would look like this