Gravitational lensing of the cosmic microwave background (CMB) is an effective probe of the projected matter fluctuation integrated along the line of sight through the observable universe. Recent measurements of the CMB lensing power spectrum are providing precise and competitive cosmological parameter constraints of the standard cosmological model LCDM, informing the “S8 tension” and further constraining the sum of neutrino masses. SPT-3G is a high-resolution, high-sensitivity mm-wave camera installed on the 10-m South Pole Telescope, ideal for measurements of CMB lensing. I will discuss the on-going CMB lensing measurements using SPT-3G data and showcase forecasts of cosmological parameter constraints with CMB lensing alone and combined with SPT-3G primary CMB spectra measurements. I will discuss the impact of extragalactic foregrounds on these measurements and on delensing for BICEP/Keck. I will conclude with field-level modeling of these foregrounds in the context of CMB lensing using generative neural networks.