Brandon once talked about Mental DNA, much like Physical or Spiritual DNA
I suspected that zinc and brass are manipulations of this Mental/Cognitive DNA as, well, its a manipulation of the mind/cognitive. Also the emotion spren on Roshar did support the idea that emotion are Cognitive in nature in the Cosmere. Zinc and brass having similar properties in fabrial science, more specifically on spren makes sense, spren are Cognitive Entities.
I suspect it seems similar to Allomancy because of the components of Allomancy: Preservation's Investiture, metal as key filtering the power to have a specific effect and an Allomancer's ability to burn certain metals, which comes from their Spiritweb or sDNA. Allomancers can burn metal from other worlds, which proves that there's nothing special about Scadrian metal. Since other people don't have the requisite sDNA, they won't be able to burn the metals, but the metals themselves can still act as a filter. I think that you can use them to filter Investiture from other Shards as well, not just Preservation. This filtering ability of these metals is Spiritual in nature