Update: working solution provided. Look at How do I compute the difference of two arrays? How do I compute the intersection of two arrays?

$list=[[1,2,6], [4,5], [7,3]];

for $vec(@$list)
{
    if(!@result)
        { @result = map {[$_]} @$vec }
    else
    {
        $origlength = @result;
        for $vecId(1..$#$vec)
        {
          for $arrId(0..$origlength-1)
            {
                push @result, [@{$result[$arrId]}, $$vec[$vecId]];
            }
        }
        push@$_, $$vec[$vecId] for @result[0..$origlength-1];
    }
}
    
use Data::Dumper;

print Dumper \@result
[download]