Considering I wrote the CAN interface for an OEM; Yes, Anything can talk to anything else... BUT...
That's why there's an interface which will only allow you to send data you're meant to send.
They also point out two vehicles with the SAME available lineup of head units and identical CAN architecture, then claim they're both the most and least secure vehicles.
Will one of my interfaces ever talk to a brake module? No, Not without a nasty firmware hack. So no, your radio won't be talking to your brakes, or engine. Sorry.