I have been on the hunt for what exact shortcut the controller hides from us. But there is a steam menu (controllers, advance, show more, at the button) that shows them!

Quickly want to change your volume? Try steam key + left joystick!

Sadly you can not change anything here, altought the menu shows you you can, nothing will be saved after you leave a menu. (I'm not a fan to put the left mouse button on the right button)

A few of them I manually found before written out, also for the people without images:

hold A + R1 + Steam
To use Puck wireless mode right

hold A + L1 + Steam
Start Puck wireless mode left

hold B + R1 + Steam
Start Bluetooth mode

When on (solid white)

Steam+Y
Turn off quickly

Hol steam (10s)
Turn off

Steam + left joystick up/down
Change volume level

R4 + R5 + L4 + L5 + Steam
Backpack mode (ignore buttons until this combo is used again or USB)

Steam + Right trackpad/joystick
Mouse movement

Steam + X
On screen keyboard

Steam + R1
Take screenshot

Steam + Menu
ALT+TAB

Steam + D-pad right
Enter key

OC by @JelleWho@lemmy.world

These shortcuts are the same for any controller. Just replace "steam button" with "PS button," "Xbox button," or "Home button" for a PS, Xbox, and Nintendo controller respectively. 3rd party controllers, too, if they happen to have that button.

There's supposed to be a way to change them, but I do not know how.

To clarify, I believe the controller has to be off to switch puck or bluetooth modes.