You can’t believe that making a small consumer electronic device was legal?

That's a bit of a mischaracterisation of the point OP was making. It is a small consumer device with a battery, that only lasts a few days and is then tossed out. That should never have been legal in the first place.

Plenty of children's toys are just as bad. All those musical toys/books you see: most of them do not have replaceable batteries - or the battery is replaceable but the retail price of the batteries is more than the whole toy (you can get sketchy batteries from the usual sketchy places for cheaper)

Agreed, but they're not being tossed out into nature the same way these disposable vapes are.

Making a consumer electronics device with the intent of it entering the regular waste stream? Fairly sure that was already illegal under WEEE, but the enforcement of that is so loose it's meaningless.