One of the really big things that nobody talks about is the invention of the "mit cheetah actuator" which was invented in (well, the paper was published) in 2017, and commercial copies became freely availble in ~2020 online for about $350-400. Xaiomi and other companies now manufacture improved, updated actuators. They are roughly shaped like a hockey puck 1.5-2.5x upscaled. These are 1) very high torque for their size and weight and 2) offer "springback" similar to human joints. Not very useful for industrial welding machines putting cars together, but for walking robots, it reduces instantaneous strain and literally puts a "spring" in their step. This allowed robots to go from being stepper motor driven (which are huge, heavy), to much more compact, which greatly improves performance, battery life, and they can actually fit in human homes etc etc