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.
Even if so, it would likely still have proprietary blobs, just embedded into a ROM or flash chip on the card. Personally, I'd rather have firmware loaded at runtime over hard-coded, at least then the blob is able to be reverse engineered possibly.
I got an Atheros card, which is fine for WiFi on Debian 12 and was cheap to buy. Drivers were in the Debian foss repo. Bluetooth is not working on it though. Interestingly, the Bluetooth did work under PureOS but I never figured out why.
Yeah maybe. I would expect PureOS to come with less non-free components though, being that it's endorsed by the FSF. I was quite surprised that BT was not working after switching to Debian.
Intel ax210 worked good for me so far, but i don't know if there are software blobs since everything worked from the get go without needing to install anything