Over the past decades, experimental quantum physics has developed rapidly in the realm of photonics, establishing a mature experimental toolbox that exploits quantum effects across a broad range of demonstrations and technologies. Representative examples include Bell tests, entanglement swapping, quantum teleportation, ghost imaging, imaging with undetected photons, NOON-state interferometric measurements, and squeezed-state metrology [1-7]. In contrast, (scanning) transmission electron microscopy ((S)TEMs) remains detached from this broader quantum toolbox. Although (S)TEMs operate intrinsically with quantum particles, they typically do not exploit quantum correlations for imaging, sensing, or measurement enhancement. Recent advances, including the experimental certification of electron-photon entanglement [8,9] and the demonstration of ghost imaging with electron-photon pairs [10], suggest a viable route toward adapting quantum schemes, and in particular, quantum photonics schemes into electron microscopy. In this work, we present a comprehensive overview and conceptual generalisation of established quantum photonic protocols to the emerging framework of electron-photon entanglement. We discuss how concepts developed in quantum optics may be translated to free-electron systems and integrated within the (S)TEM architecture. Finally, we analyse the potential opportunities offered by incorporating quantum protocols into (S)TEMs, including novel imaging modalities, quantum ghost imaging schemes, and quantum-enabled measurement strategies.