Nonconventional epitaxial techniques, such as van der Waals epitaxy and remote epitaxy, have attracted substantial attention in the semiconductor research community for their capability to repeatedly produce high-quality freestanding films from a single mother wafer. Successful implementation of these techniques depends on creating a robust, uniform two-dimensional (2D) material surface. The conventional method for fabricating graphene on silicon carbide (SiC) is high-temperature graphitization. However, the extremely high temperature required for silicon sublimation (typically above 1500°C) causes step bunching, forming nonuniform multilayer graphene stripes and an unfavorable surface morphology for epitaxial growth. Here, we developed a wafer-scale graphitization technique that allows fast synthesis of single-crystalline graphene at low temperatures by metal-assisted graphitization. In contrast to previous reports, we found annealing conditions enabling SiC dissociation while avoiding silicide formation, producing uniform single-crystalline graphene while maintaining the pristine surface morphology of the substrate. We successfully produce high-quality freestanding single-crystalline III-N (AlN and GaN) membranes on graphene/SiC via the 2D material-based layer transfer technique.