The adoption of DevOps practices in embedded systems and firmware development is emerging as a response to the growing complexity of modern hardware--software co-designed products. Unlike cloud-native applications, embedded systems introduce challenges such as hardware dependency, real-time constraints, and safety-critical requirements. This literature review synthesizes findings from 20 academic and industrial sources to examine how DevOps principles--particularly continuous integration, continuous delivery, and automated testing--are adapted to embedded contexts. We categorize efforts across tooling, testing strategies, pipeline automation, and security practices. The review highlights current limitations in deployment workflows and observability, proposing a roadmap for future research. This work offers researchers and practitioners a consolidated understanding of Embedded DevOps, bridging fragmented literature with a structured perspective.