The nitrogen-vacancy center has emerged as a promising nanoscale quantum sensor for temperature, strain, electric and magnetic fields. By integrating NV centers directly into a diamond anvil cell (DAC) --- the workhorse of high pressure science --- we demonstrate in situ measurements of magnetism inside the pressure chamber, up to ~50 GPa and for temperatures ranging from 25-340K. In addition to operating the NV in a DC-sensing modality, we also use it to perform temperature dependent noise spectroscopy of Gadolinium, directly observing the Curie transition via changes in the Johnson noise. In contrast to conventional probes at high pressure, the NV-DAC allows for diffraction-limited spatial resolution within the high pressure chamber. Time permitting, I will move away from the NV center as a quantum sensor and introduce our recent work using a strongly coupled ensemble of NV and P1 centers (substitutional nitrogen defects) to explore emergent hydrodynamics.