This demo shows how with XML simple your structure can change depending on how many devices you have in the xml.

#!perl
use strict;
use warnings;
use XML::Simple;
use Data::Dump 'pp';

my @xml=();
# 2 devices
$xml[0] = '
<xml>
<cfg>
  <device name="switch1" ip="192.168.0.1" localfile="filename1"/>
  <device name="switch2" ip="192.168.0.2" localfile="filename2"/>
</cfg>
</xml>';

# 1 device
$xml[1] = '
<xml>
<cfg>
  <device name="switch1" ip="192.168.0.1" localfile="filename1"/>
</cfg>
</xml>';

# run for each xml
for my $i (0..1){
  
  my $heap = XMLin($xml[$i]);
  
  for my $name (keys %{$heap->{cfg}->{device}}){
    push @{ $heap->{cfg}->{devices}},$name;
  }
  print pp $heap;
  
  print "\n-----------------------\n";
  foreach my $name (@{ $heap->{cfg}->{devices} }) {
    my $CFG = $heap->{cfg}->{device}->{$name}->{localfile};
    print "$CFG\n";
  }
  print "-----------------------\n";
}
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