I just installed an Intel 9260 ($20 on Amazon Prime) in my Librem 15 v4 and, voila! Excellent wifi.
The kill switch works.
Get the proprietary firmware from Intel and copy to /lib/firmware
Also, be careful when removing and reattaching the very small connectors on the antenna cables. They take very little pressure but they need to be aligned just so. In case you forget, the gray wire goes closer to the hinge.