The coherent photogalvanic (PG) effect induces an effective χ⁽²⁾ nonlinearity in natively χ⁽³⁾ silicon nitride integrated photonics, unlocking pathways toward chip-scale precision spectroscopy and optical clockworks via second harmonic generation (SHG). While quasi-phase-matched PG-SHG using spatially varying internal electric fields offers tuning flexibility, it is often accompanied by pump-power- and detuning-dependent frequency offsets. Here, we investigate whether direct phase-matching—utilizing an intermodal scheme that generates a spatially uniform electric field—can support metrologically compatible SHG. By comparing the fundamental and doubled optical frequencies in a silicon nitride microresonator, we test the preservation of the (2:1) frequency ratio in directly phase-matched PG-SHG. We observe a frequency offset of < 1 Hz, contrasting with previous limitations in quasi-phase-matched configurations. Furthermore, we measure a residual fractional frequency instability of 2× 10⁻¹⁵ at 1 s, averaging down to the 10⁻¹⁶ level at 1000 s, with multi-hour deviations remaining below 1 Hz. These results establish directly phase-matched PG-SHG as a robust, metrologically compatible route to effective χ⁽²⁾ functionality, combining sub-Hz frequency-ratio fidelity and high coherence on a mature integrated platform for optical clockworks, self-referencing, and precision spectroscopy.