All this is really to achieve front-running, executing an order after another order has been submitted but before the first order is executed. This is betting on a sure thing. It's also illegal.
Front running is when your stock broker gets an order from you but then turns around and executes an order on his own behalf before he executes yours. This is illegal because your broker has a fiduciary duty to you, his client.
It's not front running when I see an order on one exchange and then, very quickly, go make an order on a different exchange. It's not illegal because I have no fiduciary responsibility to any of the other people involved.
You have no right to execute multiple orders on different exchanges atomically.
I suspect you won't be able to find any such source. Malfeasance by trading firms makes career cases for prosecutors.
That's not to say, normatively, that that's how things should be: obviously, prosecutors are not making much of a dent in the trustworthiness of big financial firms.
Once orders hit the market it's public information and you can do whatever you want with it. If you can do it faster than anyone else then go you!