In Aus we call them gherkins. We use the pickle terminology only in specific preparations like when it's been sliced and goes on a burger. I suppose because in culinary terms, the specific flavour of the vegetable being pickled isn't really important in that case. You aren't buying the burger for the pickle, no matter what kind of pickle it is. What's important is that some kind of tang and acidity is present, like what any pickled vegetable would provide.

Even if we assume backdoors exist, your home is a low value target relative to the many large commercial operations, government offices, airports etc which use exclusively these brands. I think you're fine to leave them up, since they're still fit for the purpose you put them up for. Chances are you'll have no issues maintaining or replacing them in future if needed. At worst, hikvision et al could hypothetically see your surveillance footage, but they aren't gonna physically steal your stuff.