As they say in the Dortania documentation, get to know your hardware 1st and foremost...
There are no M.2 slots in the Latitude E6440. Otherwise you'd have had no need for your mini PCIe-to-M.2 adapter (just for antenna adapters). Do consult the E6440 owner's manual or Dell's own support forum where this was discussed many years ago.
The Latitude E6440 has 3 x mini-PCIe slots: 1 x full size (WWAN) which is combo PCIe/USB/mSATA (the one to use for a combo wifi+BT card) and 2 x half-size (WLAN + 2nd one under the WWAN slot). I know, I once had an E6440. I'm pretty sure we also have at least 1 old thread in which I actually illustrated those slots. Do use for forum Search facility...
Space is a little tight for a BCM94360CD in the E6440 but I think it would fit in the WWAN slot. I'll give you the card's measurements.
Re: Apple BCM94360CD, please refer to the dedicated thread we published back in 2014 in our R&D forum section.
Another alternative to your defective BCM94360NG installation is to opt for a BCM4352-based mini-PCIe card such as the DW1550. It's supported in Big Sur and I understand it remains so in macOS Monterey, so...