We investigate the constituent parton distribution functions of the kaon and heavy pseudoscalar mesons — D+, Ds+, Bc+, ηc, ηb, B+, and Bs0 — using the light-cone quark model. We evaluate the NLO DGLAP evolution of the quark and antiquark PDFs from the model scale to higher energy scales. We predict the kaon NLO structure functions at energy scales accessible at the upcoming Electron–Ion Collider (EIC). Drell–Yan cross-sections are computed for COMPASS++/AMBER with Carbon, Tungsten, and Aluminum nuclear targets for both isospin states of the kaon. The Mellin moment ratios are compared with available lattice QCD and theoretical model results. We demonstrate that heavier constituents carry larger momentum fractions within their respective heavy mesons.