To provide web services adapted to the users’ functional capabilities, diversity must be considered from the conceptualization and design phases of the services’ development. In previous work, we proposed a model that allows the provisioning of adapted interfaces based on users’ identity and their functional attributes to facilitate this task for software designers and developers. However, these identities and attributes are self-declared by the users, which may impact reliability and usability. In this work, we propose an extension of our model to resolve these deficiencies by delegating the identity and attributes’ provision to external certified entities. The European electronic Identification, Authentication and Trust Services (eIDAS) regulation established a solution to ensure the cross-border mutual recognition of Electronic Identification (eID) mechanisms among the European Member States. This research aims to provide an extension of this regulation mentioned above (eIDAS) to support functional attributes and connect our previously proposed model to this extended eIDAS network. Thanks to this proposal, web services can guarantee adapted and personalized interfaces while improving the functionalities offered without any previous configuration by users and, in a reliable way, since the functional attributes belong to the users’ official eID. As the attribute set provided by eIDAS nodes only contains citizens’ personal and legal ones, we also propose a mechanism to connect the eIDAS network to external attribute providers that could extend the eIDAS profile of users with their functional attributes. We deployed a pilot to validate the proposed model consisting of an identity provider, an eIDAS node supporting the extended reference code, and an attribute provider supporting functional attributes. We also designed and implemented a simple service that supports eID authentication and serves adapted interfaces based on the retrieved extended eIDAS profile. Finally, we developed an experience for getting feedback from a set of real users with different functional capabilities. According to the results, we concluded that the generalized adoption of the proposed solution in the European digital web services will significantly improve their accessibility in terms of ease of use and adaptability to users’ capacities.