Semiconductor lasers stand as pivotal elements within contemporary optoelectronic technology. Yet, their integration into heterogeneous systems is constrained by stringent lattice matching requirements. Two-dimensional semiconductors, exemplified by monolayer tungsten disulfide, circumvent these limitations by virtue of their absence of surface dangling bonds, thereby facilitating lattice-mismatch-free heterogeneous integration. Owing to their pronounced excitonic effects, these materials furnish efficient optical gain at atomic-scale thicknesses, thereby paving a novel route towards the realization of ultra-low-threshold nanolasers. Despite experimental confirmations of two-dimensional semiconductor lasers, the endeavor to further diminish laser thresholds encounters two primary hurdles: Firstly, conventional optical microcavities grapple with the simultaneous attainment of ultra-compact mode volumes and ultra-high quality factors. Secondly, the interface between the microcavity and the two-dimensional semiconductor may engender potent dielectric screening effects, along with defect-mediated non-radiative recombination processes, which ultimately impede excitonic emission from the monolayer material.