Since as far as i understand it, it should be aplicable for AOO aswell if you miss other attacks
It's actually applicable for AOO even if you didn't miss. The AOO happens on a different turn, and the rule for Sneak Attack reads "Once per turn" (anyone's turn):
Once per turn, you can deal an extra 1d6 damage to one creature you hit with an Attack if you have advantage on the Attack roll. The Attack must use a Finesse or a ranged weapon.
You don't need advantage on the Attack roll if another enemy of the target is within 5 feet of it, that enemy isn't Incapacitated, and you don't have disadvantage on the Attack roll.
Hopefully this all gets implemented whenever they add reactions.
