You can only export from the dashboard data that is in the dashboard. Therefore you need another panel with the results of a query that contains the data you want to export.
This is your first problem - how do you reverse the aggregation to get the rows you want?
Your second problem is potentially not displaying these results but still being able to export them. You might be able to do this with some CSS
<panel depends="$stayhidden$">
<html>
<style>
#hiderows table{
display: none !important;
}
</style>
</html>
</panel>
<panel id="hiderows">
<table>
<search>
<query>your deaggregation search</query>
<earliest>-24h@h</earliest>
<latest>now</latest>
</search>
<option name="drilldown">none</option>
<option name="refresh.display">progressbar</option>
</table>
</panel>Something to note is that finding the export option is easier if there is at least one page of results
