You can buy them: https://www.trackers-cam.com/en/gsm-spy-microphone/329-gsm-c...

The power strip calls you as soon as it detects a sound.

Not sure if this is the story you're thinking of, but I do recall hearing a while ago about Chinese irons and kettles that came with some, er, undocumented features:

https://www.cbsnews.com/news/hacked-from-china-is-your-kettl...

I remember Christmas cards produced in China, containing secret 'help me' messages from prisoners that were used as cheap labor:

https://www.npr.org/2019/12/23/790832681/6-year-old-finds-me...