There are some old WiFi devices with libre firmware, but they only support old WiFi standards.

https://github.com/qca/open-ath9k-htc-firmware https://github.com/chunkeey/carl9170fw http://netweb.ing.unibs.it/~openfwwf/

Some also call into the initial version of their code that is in the ROM, and don't have enough RAM to update all of the ROM to the current code. Things like the Osmocom Baseband code also do this.

https://www.osmocom.org/projects/baseband/