Usually an IQ signal is generated from a real (RF, AF, etc.) signal by a radio (by quadrature heterodyne, Tayloe demodulation, complex vector arithmetic, or otherwise). However, if you need IQ data, and the radio only generates I (or real) component samples, a Hilbert transform can be used to generate “fake” Q components (an approximation by making some ...
You could use a SOGI-based PLL. They are used for single-phase power systems.
You could use the Vd and Vq output, Vd would correspond to your input, and Vq would be your input shifted by 90 degrees.