The Furby source code is public and heavily commented. For example, it turns the microphone off when the motors are running.

Furby was the 1998 version of ChatGPT and tons of people thought it actually slowly learned English words. The NSA was alarmed. However it turned out the "learning" process was just on a timer and the "microphone" only triggers on loud sounds.
https://archive.org/details/furby-source

Furby 1998 source code : David Hampton, Wayne Schulz : Free Download, Borrow, and Streaming : Internet Archive

The source code of the firmware used in the 1998 Furby.The patent wrapper containing it was obtained and scanned by Sean Riddle (seanriddle.com).

Internet Archive
@SwiftOnSecurity Did your mirroring setup fail to get the second half of this thread to Mastodon or am I just misunderstanding the UI?