@burzlbaum
Use bootpack from here and then update it for Catalina following my Catalina Update guide in middle of the section
For Bluetooth, you'll need new kexts from Mieze here
You'll need these 3 kexts, remove the old BrcmPatchRAM2.kext from /L/E
BrcmBluetoothInjector.kext
BrcmFirmwareRepo.kext
BrcmPatchRAM3.kext