Pls check our Table widget's footer property:

https://www.koolreport.com/examples/reports/koolphp_table/footer/

https://www.koolreport.com/docs/koolphp/table/#table-settings-aggregated-footer

You could use Map process in report setup to create meta's "footer" for any column you want:

//MyReport.php 
->pipe(new Map(array(
    "{meta}" => function($meta) {
        $colMetas = $meta["columns"];
        foreach ($colMetas as $colName => $colMeta) {
            if ($footer_condition) $colMeta["footer"] = ...;
            $colMetas[$colName] = $colMeta;
        }
        $meta["columns"] = $colMetas;
        return $meta;
    }
)))

Another option is to create your "columns" setting dynamically in your Table/DataTables widget:

$columnNames = ...;
$columnSettings = [];
foreach ($columnNames as $columnName) { 
    $columnSettings[$columnName] = [
        ...
        "footer" => ...
    ];
}
Table::create([
    ...
    "columns" => $columnSettings,
]);