There's nothing supernatural about how M3GAN operates she's a robot that Gemma programs to be Cady's companion, but her drive to preserve herself is as strong as the one for protecting Cady. At the end of subsequent sequels, this process would continue, with the murderer able to transfer his essence into other Good Guy dolls, perpetually keeping himself 'alive.' His main goal was to move his soul into a human host, thereby gaining all the benefits of being flesh and blood rather than being a toy, but Chucky's power is reliant on the supernatural, which isn't as quantifiable as technology.
In the original Child's Play, serial killer Charles Lee Ray could put his vile soul into a Good Guy doll and live on.
