I believe

        kill 'INT', $pid

will not send a keyboard interrupt to the other process when on Windows. It should kill the process, but it looks to me that will not work either.

I tried the bellow code in a cmd console and neither the explicit call to kill(), nor the hardware keyboard ^C press were passed on to the child:

perl -MIPC::Open2 -E "my($pid, $in); $pid = open2('>&' . fileno(STDOUT), $in, 'cmd', '/C', 'PowerShell', '-Command',  'Sleep', '7;', 'Echo', 'Exiting'); $SIG{'INT'} = sub { kill 'INT', $pid if $pid }; sleep 3; $SIG{'INT'}->(); waitpid $pid, 0"

or just the perl code:

    my($pid, $in);
    $pid = open2('>&' . fileno(STDOUT), $in, 'cmd', '/C', 'PowerShell', '-Command',  'Sleep', '7;', 'Echo', 'Exiting');
    $SIG{'INT'} = sub { kill 'INT', $pid if $pid };
    sleep 3;
    $SIG{'INT'}->();
    waitpid $pid, 0

When kill() is invoked 3 seconds after running the above script, nothing happens. When I press ^C (within 7 sec of starting the command), still nothing.