Potassium and sodium metabisulphite will both produce SO2 which functions to sanitize and reduce competitive growth. Potassium is the preferred ingredient in wine since it will form tartrate complexes in grape wine which can remove them. Note though that country wines as a class do not contain substantial tartaric so precipitation of potassium won’t happen in that case.
As DMW has just said sodium can produce a salty taste. on a comparison basis a handy can of soda which is formulated with 30 mg sodium would scale up to 0.32 gram sodium per gallon. If i add 0.8 gram of Na meta per gallon in several rankings that only contained 0.097 gram added sodium, ,,,, not as much as we are used to in US beverages, ,,,yes I have used Na meta in wine on occasion.