it is the flavourings that add the carbs in store bought items -- they become a processed food with the added flavourings.
sugar is often an ingredient in these coatings.
this topic might be a difficult one to compose a friendly helpful answer in.
if you don't know of a product that might be beneficial
please don't take us off topic.
In places like Tesco, they sell tubs of seasoning. You could shake some of that onto the plain or salted nuts? Although they contain carbs, I sort of think how much I would actually be adding to any given thing.
Tesco or ASDA do things like Cajun, Tex-Mex and so on.