When a random Chinese manufacturer is working on Switch Mini accessories based on secret information, you don't take it too seriously. When a major game retailer adds placeholder listings to their site for Switch Mini accessories, you start to take a bit more notice.
That's what's going on today, as GAME Spain has added listings for all the items seen in the image above. There's no pics or item information to go along with the accessories, but just their listing alone is enough to fuel the Switch Mini rumors even more.
UPDATE - The listings have since been removed. As to what that means, it could go either way. We've seen retailers accidentally confirm games/hardware with listings that were shared early, and also seen retail listings that were incorrect. Your guess as to which is going on here is as good as mine.