This study establishes a baseline for muonium (Mu) charge-exchange dynamics in n-type 4H-SiC through a detailed low-energy muon spin rotation (LE-µSR) investigation. Epitaxially grown and ion-implanted samples with nitrogen and phosphorus donors were characterized to assess the effect of carrier concentration and doping method on defect formation. LE-µSR enabled nanometer-scale depth profiling of near-surface and implanted regions, revealing variations in charge carrier concentration due to fixed surface charges. The temperature dependence of the diamagnetic fraction and phase provided direct evidence of the Mu[0] to Mu[−] transition, with extracted activation energies consistent with known donor ionization energies. Additionally, high-field µSR was used to analyze the Mu dynamics, and Monte-Carlo simulations to model the Mu[0] electron capture process. The simulation results offer a quantitative method to extract free electron concentrations from LE-µSR data, enhancing its capability to characterize the activation of dopants and carrier depth profiles. We demonstrate that LE-µSR is a powerful depth-resolved tool that can provide insights for optimizing the fabrication of reliable SiC devices for power electronics.