That's not how it works. It's not like they can just pull down FreeBSD and it comes with a driver written for whatever Bluetooth hardware they have. They still have to write the driver that actually interfaces with the hardware that Sony chose to bring into the PS5. Maybe there's already a driver for the chip that Sony has, they could fork it and tweak it for the PS5, but honestly, they likely have a fairly proprietary setup. No off the shelf or upstream code will be able to do this.