https://www.pbainbridge.co.uk/2021/01/extract-list-of-google-group-members.html

Extract a list of Google Group members into a Sheet.gs

/*
Function to get existing Group Members. Their email address and role.
Paste results into a Google Sheet.
*/

function getGroupMembers() {
  
  // create empty array to push members details into
  var memberDetails = [];
  
  
  // get Google Group by email address
  try {
    var group = GroupsApp.getGroupByEmail('YOUR GROUP EMAIL ADDRESS HERE');
  }
  catch(e) {
    // issues getting Google Group
    
    // set var to false to code does not continue
    var group = false;
  }
  
  
  // check if getting Group was successful before proceeding
  if (group) {
    
    // get array of all members in Google Group and length of the array
    var members = group.getUsers();
    var membersLength = members.length;
    
    // loop through members to get their Email Address & Role ******************
    for (var i=0; i<membersLength; i++) {
      
      // get Email Address
      var memberEmailAddress = members[i].getEmail();
      
      // get Role and set as lowercase
      var memberRole = group.getRole(memberEmailAddress).toString().toLowerCase();
      
      // push details into array for later pasting into Google Sheet
      memberDetails.push([memberEmailAddress, memberRole]);
      
    }
    // loop through members to get their Email Address & Role ******************

    
    // paste collated details into Google Sheet ********************
    //get 'Group Members' sheet
    var groupMembersSheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Group Members');
    
    // get last row of data
    var lastRow = groupMembersSheet.getLastRow();
    
    // clear current sheet content
    groupMembersSheet.getRange(2, 1, lastRow, 2).clearContent();
    
    // paste in collated members details from array
    groupMembersSheet.getRange(2, 1, memberDetails.length, 2).setValues(memberDetails);
    // paste collated details into Google Sheet ********************

    
  }
  else {
    // problem getting Google Group
  }

  
}