I’ve got a BCM94360CD-based card on the way to test that theory. The adapter I got works with either.

Wireless Card & Bluetooth update

Buy a BCM94360CD (Apple P/N 653-0014) for $30 on eBay.

Buy the Shaluoman Mini-PCIe Adapter kit for $13 on Amazon.

You will also need an extension cable for the Bluetooth antenna. A pack of two costs $7.69 on Amazon.

The only gnarly part is using a wire stripper (or clever finesse with a pair of scissors) to strip both ends of the provided cable, hook and twist the wires together, and carefully apply electrical tape to insulate the wires.

(You are essentially making the "custom cable" that OSXwifi includes in its kits.)

Or you could just buy an OSXwifi kit . . . but that will run you a real pretty penny.

Or you could buy a PCI adapter and external antennas. But, you will lose one of your PCIe slots.

Edit: this should work on Big Sur 11.2.3 and probably Big Sur 11.3+ and Monterey 12. However, at the time, I stupidly clicked the button to upgrade to Big Sur 11.3+ and the update boned the cMP 5,1 that I was working on at the time . . . so I downgraded to Mojave 10.14.