I am probably dating myself with these toy posts, but the Furby and the Tamagotchi were strangely intense fads that somehow manage to creak along to this day in unexpected forms. Here’s the Tamagotchi patent:
The Tamagotchi was one of a host of virtual pet platforms that made it big in the late 90s, but it stood out and lent its name to the human tendency to love our robot vacuums: The Tamagotchi Effect. I’m not sure whether it’s something to encourage or discourage, but it’s clearly going to keep happening as we wring our hands over whether the latest chat-bot is sentient.
Besides the US, the Tamagotchi patent was filed in Japan, Europe generally, Germany specifically, China, and Canada. Those patents are now all expired, meaning you can definitely go and make your own. Just be careful to keep your feature set and appearance within the bounds of the original device, since there is still relentless innovation in the field, as shown by this 2021 design patent: