If you know how to fix a slider and pull tab, then go ahead and attach charms. If you don't, then ask yourself if you're willing to learn, or take it to LV for a possible repair.Here’s the thing though... The zipper pulls on the PSM are not as robust as those on a Speedy, Alma, etc.
Oxidation is always a consideration, but concerned more about the more delicate zipper pulls being yanked off of the bag from the weight and tension of the attached charm.