Thanks for your reply; i won’t work with firmware-level aspects of the stack, as my plan is to write the userspace daemon, while keeping the kernel-levels modules identical and to communicate to them via HCI sockets, as they are implemented by Linux and with them I can talk directly to the bluetooth controllers.
I’ll check out Android’s project and double-check for security vulnerabilities in older version of the protocols tho, so thank you again for replying.