sort of - the splenda quick packs are certainly available - 1C worth of sweetening per little pack. AFAIK no fillers to add carbs (but open to correction as I haven't read the ingredients list).
the drop by drop kind - not in US stores - I get mine from
here.
there is a resource list
here
assuming what I think is true about the liquid: I would think you could also dilute the quick pack into 1C water (water + quick pack = 1C) and then repack it yourself into a squeeze bottle for measure-for-measure use in smaller quantities. Or even in less water and use a dropper (do the math yourself to get the sweetening power per drop depending on your dilution).