Resistive Random Access Memory (RRAM) is increasingly considered a key enabler for beyond-CMOS computing, particularly in In-Memory Computing (IMC) and hardware security applications. However, its practical deployment at large scale remains limited due to the stochastic nature of filamentary switching, which introduces significant Device-to-Device (DTD) and Cycle-to-Cycle (C2C) variability. While several studies report improvements at the single-device level or under pulsed operation, a broader understanding of how material engineering influences variability and endurance at wafer scale, particularly under DC conditions, remains limited. In this work, a wafer-scale DC electrical characterization of 1T–1R RRAM devices based on HfO₂ and Al-doped HfO₂ switching layers is presented. The devices are distributed across full 200-mm wafers fabricated in a 130-nm CMOS technology fabricated at IHP, enabling population-level analysis. Wafer-scale pristine current maps reveal spatial variations in leakage behavior prior to forming, highlighting non-uniformities that are not observable at the single-device level. Subsequent electrical characterization is performed on functional devices exhibiting stable forming behavior. Within this subset, Al-doped HfO₂ devices show a reduced spread in switching characteristics compared to HfO₂, indicating improved uniformity. Multi-level operation, evaluated on representative devices, exhibit lower DTD and CTC variability across different resistance levels. Endurance measurements further emphasize the impact of material choice on reliability. Under DC cycling, HfO₂ devices sustain stable operation up to approximately 8000 cycles, whereas Al-doped HfO₂ devices remain functional beyond 27000 cycles with comparatively limited variability increase. The evolution of LRS and HRS currents shows a narrowing memory window in HfO₂ devices, while Al-doped HfO₂ devices maintain a more stable separation over extended cycles. These results indicate that material-level modifications directly influence switching stability and endurance, which are critical for reliable large-scale RRAM integration and for future IMC applications.