The original '90s furby is unironically a fantastic platform for a hardware hacker, because they were so cheaply made the whole thing runs off a single motor and a clever arrangement of cams. It would be reasonably straightfoward to pull out the 'guts', fit a motor controller and a Raspberry Pi Zero, put a camera where the IR and light sensors go, put a better mic and camera in, then hook the bastard up to GPT-4! There's a cam position sensor too so you could modulate it's speech cycle by counting the syllables in the GPT output as well as move its ears, eyes etc.

Other improvements could include high brightness RGB LEDs behind the eyes to indicate mood, an ultrasonic sensor with a second motor so the furby can turn around and make eye contact with people entering a room, and using one of the pi's GPIO pins and a suitable piece of wire as an FM radio transmitter (use a low pass filter because doing that shits out harmonics quite badly) to hijack nearby radios.