All necessary kexts are found in my E7470 bootpack for Catalina but is backward compatible
https://osxlatitude.com/forums/topic/9179-dell-latitude-e7x70-clover-uefi-only/?tab=comments#comment-95548
For Wifi:
Lilu.kext, AirportBrcmFixup.kext, FakePCIID.kext, FakePCIID_Broadcom_WiFi.kext
For Bluetooth:
BrcmBluetoothInjector.kext, BrcmFirmwareRepo.kext, and BrcmPatchRAM3.kext // Goes into /L/E
Repair permissions and rebuild cache