Open Pilot can't use your blindspot cameras or any other additional sensors in your car. If I try to merge into another lane, and someone is in my blind spot, Open Pilot will try (and will crash my car).
Super Cruise and Smart Eye don't have this problem.
And yes, I have an Open Pilot for my Lexus RX 450h.
What you're describing is the entire semi-automated driving system + driver monitoring feature. Another Apple to Oranges comparison...
It's obvious to anyone familiar with Open Pilot that it can't access OEM blindspot cameras since it only uses the Comma Two smartphone cameras and hooks into CANBUS. So I am not really sure what point you're trying to make here.