You have bit confusion here. Android is based on Linux kernel, and changes on that is directly reflected to both Linux and Android users, it does not go to other direction. We will see if this code ends up on other use as well.

The kernel is a forked Linux, compilable with clang, it has LinuxSE and seccomp enabled by default.

Everything else, including drivers post Treble, doesn't have anything to do with Linux.

I don't know much about Bluetooth in Linux, but I had the same thought. It looks like the license on this is Apache, which I would guess could be a problem.

Very unlikely, the Android driver infrastructure is quite different from Linux.