The software-defined commercial vehicle differs from its predecessors in its electronics architecture. Through centralized compute hubs and a simplified embedded mechatronics and control rim the software development changes from a functionally distributed to a cross-functionally centralized approach. One prerequisite of this split is the establishment of managed APIs between central entities and towards the rest of the vehicle system, which, for sake of easier shift to later cloud-based solutions, needs to be aligned with the interface to offboard infrastructure. This transition, however, requires much larger efforts to open the access to the rich pool of vehicle data in a non-discriminative way. Furthermore, services will gain more attractiveness if they cannot only harvest data for processing but may also (safely and securely) interact with the vehicle and its operations. The Connected Vehicle Systems Alliance (COVESA) is an open platform that targets the creation of such open API standards. In this work we explore the VSS standard and its siblings with a particular focus on its fitness for commercial vehicles. We report on its initial applications in a series-ready software-stack and assess its potential for reuse and easier development. We also give a broader outlook on other API standardization streams and the evolution of new eco-systems of open standards for software-defined vehicles (commercial and beyond).