<p>Despite the vast promise of abrupt wavefront engineering within subwavelength thickness, most optical metasurfaces are still bound to bulky and rigid substrates. Recently, metasurfaces in suspended membranes (MISMs) have attracted increasing attention due to their unique flexible, conformal properties and their ability to minimize undesired substrate effects. Most importantly, the MISM platform enables metasurface transfer and integration with non-conventional substrates and electronic/photonic devices. By summarizing multiple approaches to create MISMs with a variety of membrane and sacrificial layer materials and configurations, we demonstrate the Omni-Purpose Transfer and Integration of Metasurfaces in Suspended Membranes (OPTIMISM), overcoming the existing limitations on metasurface geometries or materials. It is particularly suitable for metasurface integration on optical fiber tips to form meta-optic probes for broad applications, including biomedical and endoscopic imaging and sensing. Considering the various configurations of membrane dielectric environment in integrated MISM devices, we performed a systematic investigation to demonstrate the strong influence of the surrounding refractive index on ultrathin metasurface design based on both conventional forward design (library search) and inverse design strategy (evolutionary algorithm). Our findings highlight the advantage of the inverse design strategy leveraging meta-atom non-local interactions, and the great potential of the MISM platform for universal and scalable metasurface transfer and integration.</p>