The distribution of services across heterogeneous edge and cloud infrastructures in Beyond 5G (B5G) and Sixth-Generation (6G) networks increases operational complexity, while existing MANagement and Orchestration (MANO) solutions remain single-domain and lack unified telemetry or autonomous cross-domain decision mechanisms. Prior work proposes cross-domain orchestration concepts, but most validations rely on simulation and overlook interoperability issues, non-stationary latency, and inconsistent Key Performance Indicator (KPI) models in real Network Function Virtualization Infrastructure (NFVI) deployments. This paper introduces a modular, technology-agnostic Zero-touch Network and Service Management (ZSM) framework that provides unified NFVI abstraction and a multi-criteria decision engine that jointly considers latency, compute load, and energy consumption for autonomous service placement, scaling, and dynamic resource provisioning. Evaluation in a real-world deployment across geographically distributed testbeds demonstrates that our ZSM framework mitigates latency spikes by up to 96%, reduces overloaded-node latency by 36%, and maintains stable performance under variable load. These results confirm the practicality and effectiveness of zero-touch, multi-domain orchestration for future 6G compute-continuum environments.
