AA messes up the velocity mapping of the look mechanics, so STs are never trained with AA. So there's no intent behind either left or right stick AA behaviour on a XIM, that's governed entirely by the game engine. Nor is there any data on how AA interacts with an ST because they're developed in the absence of AA.
Right stick AA can be manipulated by Response Rate, Polling Rate, DPI, Smoothing, Boost, Sync, Ballistics Curves etc, but they're not designed to do so. Steady Aim is the only tool in the kit that is designed for AA, but its purpose is to combat the AA bubble to assist with hitbox entry in CoD games.
SAB only affects left stick AA, so it is already separated, though not intentionally. SAB's purpose is digital input obfuscation, not left stick AA. However, the acceleration from 0-100% over roughly 30ms in SAB plays friendlier with LS AA than digital WASD that pegs straight from 0 to 100. When using a kb without SAB, you won't feel LS AA at all, which helps rather than hinders hitbox entry, but there is no sticky AA feeling to LS movement.
True analog input is better than SAB because you can easily hold a value of less than 100% input speed to capitalise on LS AA. You can't do that with SAB, it'll always go quickly to 100% and stay there until a change of direction.