As a Deck haver/user:

Steam Input

Added missing buttons to Mode Shift Button selection menu: Left Stick Touch and Right Stick Touch

Button Chord Activator's drop down list of available buttons has been replaced with a multi button selector. This means that newer controllers have full access to extra grip buttons that were previously unlisted.

Gyro to Joystick Camera's Minimum Joystick Output now matches Gyro to Joystick Deflection's behavior, which is useful for identifying a game's internal joystick deadzone.

Improved input latency while controller rumble is happening on third party controllers.

Added option to apply Gyro to Joystick Deflection range remapping and acceleration settings on an Per-Axis or Circular basis.

Fixed a bug in Gyro To Joystick Deflection mode where a setting of 0 for Minimum Gyro Deflection, and any non zero Minimum Joystick Output would still result in zero output without a significant amount of gyro deflection. This should help gyro users to dial in games' internal joystick dead zone size more easily.

... I had, for months, been trying to tweak most of these exact things, and thought I was going insane, as nobody I could find anywhere online discussing this kind of stuff seemed to even be aware of these problems.

So its nice to know that I am not insane, and that these things have been fixed.