Not builtin, it's a card on the motherboard, WIFI/Bluetooth combo. I don't know the model off the top of my head, it's Intel though not broadcom.
Edit:
Vendor ID: 0x8087
Product ID: 0x0AA7
Intel 3168 A/C Wifi + Bluetooth
Log:
2019-11-02 20:39:48 -0400
Assertion status system-wide:
BackgroundTask 0
ApplePushServiceTask 0
UserIsActive 1
PreventUserIdleDisplaySleep 0
PreventSystemSleep 0
ExternalMedia 0
PreventUserIdleSystemSleep 0
NetworkClientActive 0
InternalPreventSleep 1
Listed by owning process:
pid 112(hidd): [0x00000016000980a3] 00:00:00 UserIsActive named: "com.apple.iohideventsystem.queue.tickle serviceID:1000009bc name:AppleHIDKeyboardEve product:Magic Keyboard with eventType:3"
Timeout will fire in 600 secs Action=TimeoutActionRelease
pid 70(powerd): [0x0000046f000d8401] 00:00:14 InternalPreventSleep named: "com.apple.powermanagement.acwakelinger"
Timeout will fire in 30 secs Action=TimeoutActionRelease
pid 70(powerd): [0x0000046f000d8400] 00:00:14 InternalPreventSleep named: "PM configd - Wait for Device enumeration"
Assertion applied on Battery power also
Kernel Assertions: 0x8=BT-HID
id=506 level=255 0x8=BT-HID mod=12/31/69, 7:00 PM description=com.apple.driver.IOBluetoothHIDDriver owner=AppleHSBluetoothDevice
id=507 level=255 0x8=BT-HID mod=12/31/69, 7:00 PM description=com.apple.driver.IOBluetoothHIDDriver owner=AppleHSBluetoothDevice
Idle sleep preventers: IODisplayWrangler