You don't even need AUTOLOAD, just create the subroutine when the other module wants to import it. Exporter is not the ideal tool for that:

sub import {
    my( @wanted )= @_;
    my( $target )= caller;

    for my $name (@wanted) {
        no strict 'refs';
        
        my $key= substr $name, 3; # is_${key}
        "$target\::$name" = sub {
            my( $reg ) = @_;
            ...
        };
    };
};
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