Wi-Fi and Bluetooth firmware for Linux on T2 Macs.

The firmware has been extracted from macOS GitHub Runner Image.

Ubuntu/Debian

Ubuntu and Debian users can add the apt repo for firmware by running:

curl -s --compressed "https://adityagarg8.github.io/t2-ubuntu-repo/KEY.gpg" | gpg --dearmor | sudo tee /etc/apt/trusted.gpg.d/t2-ubuntu-repo.gpg >/dev/null
echo "deb [signed-by=/etc/apt/trusted.gpg.d/t2-ubuntu-repo.gpg] https://github.com/AdityaGarg8/Apple-Firmware/releases/download/debian ./" | sudo tee -a /etc/apt/sources.list.d/t2.list
sudo apt update

Then install the apple-firmware package by running:

sudo apt install apple-firmware

For more details refer to this t2linux wiki.