This paper presents a high-fidelity optical readout technique for a nuclear spin qubit based on the V2 center in 4H-SiC. The authors demonstrate a readout fidelity of up to 99.5% and a state preparation fidelity of 99%. They achieve this by using a repetitive readout technique that maps the nuclear spin state onto the electron spin state. The study also includes measurements of Rabi oscillations and Ramsey dynamics, showing a coherence time of 7.4(4) ms. Additionally, the authors apply the efficient readout for quantum sensing, probing weakly coupled nuclear spins using ENDOR spectroscopy. The results highlight the potential of the V2 center in 4H-SiC as a qubit candidate for quantum information processing and sensing applications.This paper presents a high-fidelity optical readout technique for a nuclear spin qubit based on the V2 center in 4H-SiC. The authors demonstrate a readout fidelity of up to 99.5% and a state preparation fidelity of 99%. They achieve this by using a repetitive readout technique that maps the nuclear spin state onto the electron spin state. The study also includes measurements of Rabi oscillations and Ramsey dynamics, showing a coherence time of 7.4(4) ms. Additionally, the authors apply the efficient readout for quantum sensing, probing weakly coupled nuclear spins using ENDOR spectroscopy. The results highlight the potential of the V2 center in 4H-SiC as a qubit candidate for quantum information processing and sensing applications.