Sergio Sánchez

Sergio Sánchez is not mentioned in either of the provided news articles. Therefore, it's impossible to provide any information about who he is, why he's newsworthy, recent events related to him, or his current relevance based on the given context. The articles focus on Telefónica's drone business and Julio Martínez's refusal to testify in the Koldo commission, respectively. Without additional information, any details about Sergio Sánchez would be speculative and inaccurate.