Borderlands 2 on Steam Deck: Trackpad + Gyro Steering and Shooting is TOO FUN! (Handcam Gameplay) 

I know the video looks shaky, but it's not an issue when you're actually playing the game. Gyro aiming adds an element of immersion, control, and fun that you just can't get with computer-assisted stick aiming. Trackpad turning makes it even better! Both fast turns and small adjustments are so effortless...
My key settings for most first-person shooters:
Change Primary Fire to Left Trigger (more comfortable and easier to repeatedly fire without causing your right aiming thumb to jitter)
Right Trackpad
Vertical Scale: 50
Smoothing: 40 (Maximum)
Trackball Mode: On
Trackball Friction: Medium
Sensitivity: Raised to let me do a 180 with a firm swipe
Gyro
Smoothing: 0 (None)
Activated on Right Pad Touch
Sensitivity: Raised to let me look nearly directly upward when I rotate my wrists to my highest comfortable angle