Alchemical items such as alchemist's fire, acid flasks and tanglefoot bags don't have any size limitations for creatures using them. They also don't require a weapon proficiency.
Does this mean a familiar could throw an alchemical weapon on their initiative turn?
Familiars that can use wands likely can, but it really depends on the familiar, toads/frogs, lizards, and snakes not likely, but you could burn a feat for an evolution point for an extra limb/hand as a possibility.