Without revisiting the schematics, I'll say "no" until someone confirms it.
But converting RS232 to as much GPIO as you care to multiplex is do-able, even with off-the-shelf controllers. However I'm not aware of any that are cheap (think obscure industrial automation) nor any that would work at the PBPs baud rate. But if you're savvy you could make your own controller with a BASIC Stamp, Arduino, or even RockPro64.
What's even easier and much cheaper, is USB GPIO. You can even hide this inside the case (I've already thought about doing this).
But converting RS232 to as much GPIO as you care to multiplex is do-able, even with off-the-shelf controllers. However I'm not aware of any that are cheap (think obscure industrial automation) nor any that would work at the PBPs baud rate. But if you're savvy you could make your own controller with a BASIC Stamp, Arduino, or even RockPro64.
What's even easier and much cheaper, is USB GPIO. You can even hide this inside the case (I've already thought about doing this).