I was thinking of getting a wifi card like that, but can’t seem to find any.
Not very modern, but this card is also available on Novacustom Laptops
Use libre boot website’s info for reference. The Athero cars were the only open source option. They are from the aughties. That is your only option. It is the same for hardware - libre boot stuff with a Core Duo era processor, nothing newer is trusted hardware.
For something relatively fast, I suggest you stick to Intel chipsets, and avoid realtek like the plague. As others mentioned, you can go with Atheros, but your speed will certainly suffer, as well as probably breaking the ability to put the computer to sleep with S3.
I understand you would rather go with 100% FOSS, but this carries trade-offs.
You could always get an Ethernet-connected AP. This will allow you to use the latest WiFi but not compromise your OS.
