On the Pyra I used the puck, which has it's own bootloader (you can actually connect to it with minicom and run commands).
If that detects Steam it switches to controller mode, if not it goes into a fallback mode (Lizard mode?) which acts as a mouse and keyboard.
In this mode you can control the Pyra to, move the mouse and click on stuff.
Because the bootloader determines how the controller should act, which interface later is used doesn't really matter as those signals aren't send by the controller.
You can make your own puck with a customer firmware, which allows you to force-switch the controller into the controller mode.
Opensource firmware for NRF52840 Pro Micro that copycats the Steam Controller 2 Puck and adds an Xbox and Switch mode - safijari/openpuck
github.com
Steps which I will try later (but probably fail, I think it requires the latest SDL):
sudo nano /etc/udev/rules.d/99-steam-controller-v2.rules
# Valve USB Puck / Dongle (2026)
SUBSYSTEM=="usb", ATTRS{idVendor}=="28de", ATTRS{idProduct}=="1205", MODE="0666"
SUBSYSTEM=="usb", ATTRS{idVendor}=="28de", ATTRS{idProduct}=="1105", MODE="0666"
# Xbox/Gamepad emulation via uinput
KERNEL=="uinput", MODE="0660", TAG+="uaccess", OPTIONS+="static_node=uinput"
sudo udevadm control --reload-rules
sudo udevadm trigger
--> indeed doesnt work as HIDRAW in not set in the kernel.
I did get this running on the Pyra, but won't help:
https://github.com/C0rn3j/sc-controller