if the $x pattern I am looking for is from uc(chomp($x = <STDIN>)), would I just need to use split, inserting the ^A-Z* after every character? would that work?

Yes, you would do this:

my $x = <STDIN>;
chomp $x;
$x = uc($x);
my $regex = join('[^A-Z]*', split //, $x);
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