Add a 'Finalize Registration Step' to the registration report, if the user completed the finalize registration step the field will show 'Complete', otherwise it will show 'Incomplete.

functions.php

<?php //Please do not include the opening PHP tag if you already have one 

function ee_tw_reg_step_status_to_csv( $reg_csv_array, $reg_row ) {
  
  $transaction_reg_steps = unserialize( $reg_row['TransactionTable.TXN_reg_steps'] );
  
  $reg_csv_array['Finalize Registration Step'] = '';

  if( isset($transaction_reg_steps['finalize_registration']) ) {
    $reg_csv_array['Finalize Registration Step'] = $transaction_reg_steps['finalize_registration'] == TRUE ? 'Complete' : 'Incomplete';
  }
  return $reg_csv_array;
}
add_filter( 'FHEE__EventEspressoBatchRequest__JobHandlers__RegistrationsReport__reg_csv_array', 'ee_tw_reg_step_status_to_csv', 10, 2 );