Can I self declare that my product complies to the standards?

Considering CE marking manufacturer’s choice to go for module A and self declare that the product complies and does not need to use a third party test lab, it is possible for harmonized standards. For example you can self declare EMC and safety articles 3.1 a and 3.1 b. You even can self declare the radio part 3.2 if harmonized standards are used to meet the essential requirements in full.

If in the future there would be harmonised standards for the cyber security part, you can even self declare for articles 3.3 d, e, f.

The downside of self declaring, is that for your costumers it would impress them more if you have certification by an independant party than that you would self declare it.

Also the test equipment needed to do the self declaration is not cheap and most manufacturers don’t have this specialized test equipment. So its easier and cheaper to go to a specialist for testing.