A microscopic description of nucleon–nucleon (NN) and nucleon–nucleus (NA) scattering is developed using chiral effective field theory () at next to next to next to leading order N[3]LO. The NN interaction is taken from the EGM formulation, which incorporates spectral function regularization to control short range components of the two pion exchange force, together with a Gaussian regulator to ensure convergence of the Lippmann–Schwinger (LS) equation. The regulator parameters (, ) = (450,500), (550,600), (600,600) MeV. The resulting NN t-matrix is used to construct the first order optical potential, from which Wolfenstein amplitudes and elastic differential cross sections are calculated. The theoretical amplitudes (B) and (C) for pp and pn scattering at 100 and 200 MeV show good overall agreement with those reconstructed from the SAID partial-wave analysis of the experimental data, with the largest discrepancies appearing in the small real component of the spin orbit amplitude. Calculations of p + [16]O and p + [40]Ca elastic scattering at 100 and 200 MeV reproduce the measured angular distributions with high accuracy, particularly at forward and intermediate angles. These results demonstrate that the EGM potential provides a consistent and quantitatively reliable framework for describing NN observables and NA elastic scattering in the 100-200 MeV energy range, while highlighting the need for improved treatment of short range and spin dependent contributions at higher energies.