This paper investigates heat and mass transfer phenomena by assessing advanced thermal conductivity models (TCMs) that significantly influence the flow of metallic (Au) nanoparticles under suitable boundary conditions. By integrating high TCMs with innovative interfacial fractal theory, we demonstrate a marked enhancement in thermal and concentration transfer. The analysis further investigates the physical model of a hybrid porous channel under the influence of nanofluid flow, magnetohydrodynamics (MHD), and chemical reactions. A detailed numerical investigation of nonlinear partial differential equations, converted into higher-order nonlinear ordinary differential equations (ODEs) using similarity transformations, reveals results by employing single-phase models of nanofluids. The ODEs are solved numerically via the shooting approach combined with the fourth-order Runge–Kutta method, using Mathematica to produce both graphical and numerical results. A comparative graph for expanding/contracting cases deliberated under the impact of MHD and chemical reaction. For expanding and suction cases, volume fractions of nanoparticles increase the function of the Nusselt number. Similarly, MHD is also an increasing function of shear stress near the porous surfaces. As the radius of the nanoparticle (dp) and the inter-particle spacing (h) increase, the radial velocity and temperature profiles also rise in both porous walls. It shows that chemical reactions alter thermal and mass transfer characteristics, with optimal parameters identified for maximizing efficiency. The research uncovers nonlinear interactions between flow dynamics and nanoparticle characteristics, explores the impact of external magnetic fields, and examines how boundary conditions influence transfer processes. Overall, this work enhances our understanding of using fractal theory to improve heat and mass transfer in engineering applications involving metallic nanoparticles.