The Mikey ASIC (Atari Lynx)
The Mikey chip is one of two ASICs on the Atari Lynx.
The console will not operate at all without both chips present.
The Mikey is clearly responsible for audio, driving the LCD, power on control, and likely reading and running the game code, based on the schematic.
We know from this discovery that although the Hayato/Mikey drives the LCD, but the pixel data it puts out on the DLx pins actually comes from the Suzy.
The pinout is below.