If you are doing a lot of such lookups then you may find it worthwhile to index @PEOPLE.

my %PEOPLE_index;
for my $ppl (@PEOPLE) {
  while ( my ( $k,$v) = each %$ppl ) {
    push @{$PEOPLE_index{$k}{$v}} => $ppl;
  }
}

for my $ppl ( @{$PEOPLE_index{fname}{John}} ) {
  #....
}
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