What Asahi are doing is more like reverse engineering of drivers and the interface between drivers and hardware/firmware.
The issues Debian is talking about are more about the firmware blobs needed for WiFi devices. The Linux drivers exist and are included in Debian, but the software running on the WiFi device is proprietary software is not pre-installed on the device but instead uploaded by the Linux driver to the WiFi device at boot time and then runs on the WiFi device itself.
