Resource distribution among diverse administrative domains, network operators, and geographical locations across the edge-to-cloud continuum requires suitable communication and management and orchestration (MANO) mechanisms among orchestration domains. In multi-access edge computing (MEC) environments, efficient application lifecycle management and system federation are essential for scalability, optimal resource utilization, and ensuring service continuity and reliability. Existing orchestration solutions, typically designed for centralized cloud architectures, often fall short in accommodating application delay requirements and in managing the dynamic and distributed nature of MEC resources effectively. This paper introduces a cloud-native, platform-agnostic MEC Orchestrator (MEO) with enhancements over the ETSI MEC architecture, albeit aligned with GSMA and ETSI MEC federation standards, that supports cross-platform MANO and resource controllability. Federation is supported through a new MEO-to-MEO interface that enables application migration across MEC systems. Experimental results demonstrate a 95% instantiation success rate for instantiation, overperforming the baseline Kubernetes scheduler, and 93.3% for migration requests within federated MEC systems in high request volume scenarios.