Easy see the upstream contributions from any commercial vendor that has integrated BSD into their UNIX flavours, or the alternatives that exist nowadays for embedded FOSS operating systems, none of them GPL.
Where can I get the source of the exact kernel running on iOS devices, including all drivers?
How about the Playstation 4 or 5? Where can I get the source of their FreeBSD fork?
No, most drivers are closed source and you can just extract binary blobs for them. They run as daemons that communicate through the binder ipc - Android basically turned the Linux kernel into a microkernel.
Traditional Linux drivers are considered legacy in Android.