Single electron spins in silicon can be used to realize quantum bits (qubits) that profit from the long coherence times inherent to the host material. When confined in quantum dots (QDs) under electrostatic gates in a silicon metal-oxide-semiconductor (Si-MOS) architecture, there is the added promise of scalability provided by the well-established industrial semiconductor manufacturing technology. However, most Si-MOS spin qubits produced to date employ quantum state readout via spin-dependent-tunnelling to an electron reservoir. This requires significant on-chip real estate, making it difficult to be implemented in large scale multi-qubit devices. Here, we address this challenge by combining coherent spin control with high-fidelity, single-shot, singlet-triplet readout. We employ Pauli-spin blockade in a double QD as a readout tool to achieve a fidelity of \(99.3\) \(\%\). This readout scheme allows us to implement coherent electron spin resonance (ESR) control at magnetic fields as low as \(150\) mT, corresponding to a carrier frequency of 4.2 GHz, eliminating the need for high-frequency microwave sources. We discover that the qubits decohere faster at low magnetic fields with \(T_{2}^\text{Rabi}=18.6\) \(\mu\)s and \(T_2^*=1.4\) \(\mu\)s at \(150\) mT. Their coherence is limited by spin flips of residual \(^{29}\)Si nuclei in the isotopically enriched \(^{28}\)Si host material (\(800\) ppm \(^{29}\)Si), that occur more frequently at lower fields. This finding highlights the importance of further isotopic enrichment of silicon substrates for the realization of a scalable quantum processor using Si-MOS technology.