Edit to add: It appears that the “mt76” Wi-Fi 6 driver is open source:
https://en.wikipedia.org/wiki/Comparison_of_open-source_wireless_drivers#Status

Pardon my ignorance, but what Linux device driver(s) does one use for the Wi-Fi 6 11ax 4T4R Mini PCIe Module (AW7915-NP1)? I’ve been under the (hopefully false) impression that open source drivers don’t exist for Wi-Fi modules beyond the 802.11n (A.K.A. Wi-Fi 4) standard.

Edit to add:
Maybe the driver really is open source? I’m not familiar with Linux kernel/driver foo, so I’m not really sure, but this doesn’t look like a binary blob to me: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/net/wireless/mediatek/mt76/mt7915
The code seems to be under the ISC license, which I’ve never encountered before, but it seems to me an open source license.