Expanding on dcmertens' suggestion:

This hack shows how to define ONE module (here "Classy" YMMV) which creates as many types and package variables in the callers package as you want to.

use strict;
use warnings;
use lib '.';

use Classy ;

my Str $a ="Goliath";       # no compilation error

$var //= 'Philistine';      # no compilation error

print $var;
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module

package Classy;
use strict;
use warnings;


sub import {
    my $pkg = (caller())[0];
    eval 'require Str';
    
    no strict 'refs';

    *{"${pkg}::var"} = \(my $var);
    

}

1;
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