OK, this ain't pretty...

use 5.010;
use Lexical::Types;
use Hash::FieldHash qw(fieldhash);

BEGIN { fieldhash %::_TYPE_TRACKER }

BEGIN {
    package Foobar;
    sub TYPEDSCALAR { $::_TYPE_TRACKER{\$_[1]} = $_[2] }
}

my Foobar $foo = "Hello";
say $::_TYPE_TRACKER{ \$foo };
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