Presupposing that 'country' and 'currency' will always be unique keys (and renaming your old %countryMap to %codeMap because the label made more sense to me in this case), this would work...

my %codeMap = ( US => { country => 'USA', currency => 'USD'} );
my %currencyMap = map { $codeMap{$_}{currency} => $_ } keys(%codeMap);
my %countryMap = map { $codeMap{$_}{country} => $_ } keys(%codeMap);
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But, you probably want to use a database for this.
Hope this helps!

--jwest

-><- -><- -><- -><- -><-
All things are Perfect
    To every last Flaw
    And bound in accord
         With Eris's Law
 - HBT; The Book of Advice, 1:7