On normal MacOS, I can use the keyboard shortcut option + shift + volume up/down to change the volume in smaller increments.

I want to do this using a custom gesture on my MX Master 3s that preforms the keyboard shortcut, but Logi Options + doesn't let me all the volume up/down buttons to a keyboard shortcut.

Therefore, I am suggesting that there should either be an option to change the volume in smaller increments using custom gestures, or let us add the volume up/down buttons to keyboard shortcuts in custom gestures.