Does the labelling requirement apply to free products I don't mention?

No. As long as you don't mention or show the product in a post, there is no labelling requirement. The matter becomes relevant only once you actively present or discuss the gifted product—then it counts as consideration under Federal Court of Justice case law, even if no money changed hands. An exception applies where a product merely appears incidentally as a prop in the image without being promoted; in this case, goods valued up to €1,000 are harmless under standard interpretation. However, as soon as you mention the product positively, link to it or recommend it, you should label it to avoid risk.