Ground-based cosmic microwave background (CMB) experiments are now pushing into discovery space where new insights on inflation, dark matter, dark energy and neutrino physics will be obtained by unraveling signatures buried beneath the primordial fluctuations. I will present new results from the Atacama Cosmology Telescope (ACT) that exemplify the power of high-resolution measurements of the microwave sky, including high-fidelity maps of dark matter through gravitational lensing. These maps set the stage for a robust measurement of the neutrino mass scale and hierarchy with upcoming ACT and Simons Observatory data. Even more discovery potential is opened up when cross-correlating with galaxy surveys like the Rubin Observatory. Optimally extracting the joint cosmological information in CMB and galaxy surveys requires novel data analysis techniques. I will present developments in the use of simulation-based inference as well as fast techniques that approach maximum-likelihood performance for cosmological data, and put these in the context of large cosmological surveys planned over the next decade.