BCM92045NMD for BT in Big Sur

In High Sierra and Catalina I used without problems a BCM92045NMD board (coming from an old laptop) converted to USB (I call it "The BT flower" :) ).

https://imgur.com/a/51UcEzU

Now I installed Big Sur, everything works but the BT board. I followed the OpenCore tutorial and informations on github pages of the kexts, especially trying with brcmfx-driver boot arg (from 0 to 3), without it and setting MaxKernel to 19.9.9 for AirPortBrcm4360_Injector.kext.

In the Kexts folder I have: AirportBrcmFixup.kext, BlueToolFixup.kext, BrcmBluetoothInjector.kext, BrcmFirmwareData.kext and BrcmPatchRAM3.kext.

The BT cannot be activated because the board is not recognized at all by the system.

Is it possible that this board is not supported anymore in Bug Sur? Any suggestion? Thanks!