Not really.
What i mean are normally a reversing camera come alive when you engage reverse, this the headunit sense and then switch to the AV channel of the camera.
The AV out of the dashcam are always on so you would have to switch away from the AV channel if you put it on same channel as reversing camera with a splitter of some sort.
If there are more AV in on the Toyota headunit then it might work.
But why look at a little low resolution screen when you can look out the window and get the lords full blown HDR 8K package ?