I'm making an action game in Unity, where the player character can hold an item in either hand, and some objects are held in both. I want the PC to be ambidextrous, so I essentially need to be able to "mirror" hand positions, including finger orientations.
To illustrate what I mean, one of the guns in the game is a pistol with a forward grip: if the gun is held in the right hand (the grip is in the right hand), then the left hand grasps the forward grip; if the player holds the grip in their left hand, then it's vice-versa.
How I'm doing this is to have basically a copy of the hand armatures saved for each item, posed in the configuration the PC's hands should be in, and then I match those transforms when the item is held (I'm using IK to get the hands in the correct place). What I would like to be able to do is mirror those hand positions for the "left hand" hold of an object. Are there any best practices for doing things like this, having animations/poses be symmetrical or reversible or whatever you want to call it? Should I set up the PC model's rigging in a particular way, or is there some more simple way to mirror the positions?