Is there a way to return data from a database call as an general object rather than a specified type, without creating a new class

Question

I have a function that is trying to return a list of all transactions from the database. To do this it needs to retrieve all the data from TransactionItems, and then join that to the data retrieved from Transactions. I want to be able to do this without creating any new classes (if at all possible)

  public async Task<IEnumerable<object>> GetTransactionBySaleId(int id)
  {
      var query = ("SELECT t.*, ti.* " +
         "FROM Transactions t " +
         "INNER JOIN TransactionItems ti ON t.SaleId = ti.SaleId " +
         "WHERE t.SaleId = @Id");

      // Parameterisation to prevent injection attacks
      var idParam = new SqlParameter("Id", id);

      return await DatabaseConnection.Instance.ExecuteQueryAsync<object>(query, idParam);
  }

My ExecuteQueryAsync method:

public async Task<IEnumerable<T>> ExecuteQueryAsync<T>(string query, params SqlParameter[] parameters) where T : new()
 {
     using var connection = new SqlConnection(connectionString);

     await connection.OpenAsync();

     var resultList = new List<T>();

     using var command = new SqlCommand(query, connection);

     // Add parameters to the command if any
     if (parameters != null)
     {
         command.Parameters.AddRange(parameters);
     }

     using var reader = await command.ExecuteReaderAsync();
     
     while (await reader.ReadAsync())
     {
         var obj = new T();
         MapData(reader, obj);
         resultList.Add(obj);
     }
     
     return resultList;

 }

My issue is that the return type is currently object, and all this does is return empty objects for each entry in the tables. I first had it set to return Transactions but this didn't display the data from TransactionItems.

Data in my Transactions table: Transactions

Data in my TransactionItems tale: TransactionItems

I'm still relatively inexperienced, so any help would be appreciated