I'm not sure its quite so simple as that.
There are lots of sounds/noises the car makes that go through the car's sound system - reversing sensors on mine and lots of dings for belts, ignition and other stuff.
I'm not that clued up with how stereos/head units/infotainment systems work these days. There may be an amp in the car bespoke to the head unit in the car (the LCD bit?).
Mine doesn't have an LCD. I can get an aftermarket Android unit that replaces the cubby hole space at the top of the dash. They come with dash mouldings that fit in and 'look original'. These units though, I believe, simply plug into the existing stereo (head unit?) via the aux port. So the original stereo is responsible for distributing the sound out to speakers and will still be hooked up to the car's systems that use the sound system for interaction with the driver.
It does my head in how complicated this stuff all is these days, which is probably why I've never really taken the time to fully understand it. What I do know though, is that even though I have the most basic of F2 sound systems, its fookin good quality (compared to everything I've had previously).