This works:
Foo.pm:

package Foo;

use strict;
use warnings;

use base 'Exporter';

our $hello = \&hellosub;
our @EXPORT_OK = ( '$hello');

sub hellosub {
    my $h = shift;
    return $h;
}

print $hello->("Foo Mod init"),"\n";

1;
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test caller code:

use strict;
use warnings;
BEGIN {
    push ( @INC,".");
}
use Foo ('$hello');

print $hello->('test'),"\n";
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