I'm not familiar with the games or videos, but my guess is that normally, firing in a shooter and grabbing in the goose game are done by clicking the mouse. But clicking the mouse might cause the mouse to move, messing up your aim. To solve that, you can change the fire/grab mapping to happen when you scroll your mouse instead of when you click your mouse.

I'm not particularly good at shooters and part of the reason is that I can't seem to be able to hold the mouse perfectly still when clicking.

Rolling the mouse wheel is a different movement and somehow that helps, especially with weapons that are powerful(and thus have significant recoil), but have a relatively low rate of fire.

With this binding I saw the greatest improvement in using the Guardian in Valorant:

https://valorant.fandom.com/wiki/Guardian?so=search

I could just aim and go Pew Pew Pew Pew, which exhausted the length of my scrolling finger, but was typically enough to drop or severely damage anyone I was aiming at.